Decimals, Fractions and Percentages

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Decimals, Fractions and Percentages

Decimals, Fractions and Percentages are just different ways of showing the same value:

A Half can be written…
As a fraction:
1/2
As a decimal:
0.5
As a percentage:
50%

 

A Quarter can be written…
As a fraction:
1/4
As a decimal:
0.25
As a percentage:
25%

Here, have a play with it yourself:

Example Values

Here is a table of commonly occuring values shown in Percent, Decimal and Fraction form:

Percent Decimal Fraction
1% 0.01 1/100
5% 0.05 1/20
10% 0.1 1/10
12½% 0.125 1/8
20% 0.2 1/5
25% 0.25 1/4
331/3% 0.333… 1/3
50% 0.5 1/2
75% 0.75 3/4
80% 0.8 4/5
90% 0.9 9/10
99% 0.99 99/100
100% 1
125% 1.25 5/4
150% 1.5 3/2
200% 2

 

Conversions

 

From Percent to Decimal

To convert from percent to decimal: divide by 100, and remove the “%” sign.

The easiest way to divide by 100 is to move the decimal point 2 places to the left. So:

From Percent To Decimal
move the decimal point 2 places to the left, and remove the “%” sign.

 

From Decimal to Percent

To convert from decimal to percent: multiply by 100, and add a “%” sign.

The easiest way to multiply by 100 is to move the decimal point 2 places to the right. So:

From Decimal To Percent
move the decimal point 2 places to the right, and add the “%” sign.

 

From Fraction to Decimal

The easiest way to convert a fraction to a decimal is to divide the top number by the bottom number (divide the numerator by the denominator in mathematical language)

Example: Convert 2/5 to a decimal

Divide 2 by 5: 2 ÷ 5 = 0.4

Answer: 2/5 = 0.4

 

From Decimal to Fraction

To convert a decimal to a fraction needs a little more work.

Example: To convert 0.75 to a fraction

Steps Example
First, write down the decimal “over” the number 1 0.75 / 1
Then multiply top and bottom by 10 for every number after the decimal point (10 for 1 number, 100 for 2 numbers, etc) 0.75 × 100 / 1 × 100
(This makes it a correctly formed fraction) = 75 / 100
Then Simplify the fraction 3 / 4

 

From Fraction to Percentage

The easiest way to convert a fraction to a percentage is to divide the top number by the bottom number. then multiply the result by 100, and add the “%” sign.

Example: Convert 3/8 to a percentage

First divide 3 by 8: 3 ÷ 8 = 0.375,
Then multiply by 100: 0.375 x 100 = 37.5
Add the “%” sign: 37.5%

Answer: 3/8 = 37.5%

 

From Percentage to Fraction

To convert a percentage to a fraction, first convert to a decimal (divide by 100), then use the steps for converting decimal to fractions (like above).

Example: To convert 80% to a fraction

Steps Example
Convert 80% to a decimal (=80/100): 0.8
Write down the decimal “over” the number 1 0.8 / 1
Then multiply top and bottom by 10 for every number after the decimal point (10 for 1 number, 100 for 2 numbers, etc) 0.8 × 10 / 1 × 10
(This makes it a correctly formed fraction) = 8 / 10
Then Simplify the fraction 4 / 5

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Ecology Quiz

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Ecology
  1. Which two biomes are the most similar with regard to rainfall?
    tundra & taiga
    tundra & desert
    rain forest & savanna
    temperate forest & prairie
  2. Which biome is characterized by a layer of permafrost?
    taiga
    savanna
    chaparral
    tundra
  3. Biodiversity is greatest in which biome?
    taiga
    polar
    rain forest
    savanna
  4. The eastern portion of the United States is dominated by what biome?
    temperate forest
    desert
    taiga
    prairie
  5. In which biome of Africa would you find lions, giraffes, and elephants?
    savanna
    chaparral
    desert
    tropical rain forest
  6. All the different species of an ecoystem are referred to as the:
    biome
    community
    population
    abiotic factors
  7. Which of the following would represent an ecosystem?
    A lake
    A fish tank
    A prairie
    all of these
  8. All the nonliving parts of an ecosystem are referred to as:
    the community
    biotic factors
    abiotic factors
    biomes
  9. Which of the following would be a biotic factor in an ecosystem?
    bacteria
    soil
    temperature
    rainfall
  10. The types and numbers of species in a given area is most greatly determined by the area’s:
    biotic factors
    precipitation
    climate
    biodiversity

Score =
Correct answers:

Evolution Quiz

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Evolution
    1. In biological terms, what is a species? a group of organisms that are similar in form and structure
      a group of organisms that can interbreed
      a group of organisms that share common features
      a group of organisms that have live in the same habitat
    2. What is the Scala Naturae? an idea proposed by Darwin that suggests that all organisms share a common ancestor
      an idea proposed by Plato that suggests organisms are all evolving toward an ideal form
      an idea proposed by Aristotle that suggests that all organisms fit into an orderly scheme
      an idea proposed by Wallace that suggests that organisms change over time
    3. Creationism is not accepted as a valid scientific theory because: it violates the scientific principle of natural causality
      it doesn’t offer a model to explain the diversity of life on earth
      it cannot be disproven
      all of these

birds

    1. The picture of the finches is used to illustrate: phylogeny of finches
      change over time
      specialization of beaks for different diets
      natural selection
    2. Which of the following was not an observation made by Darwin on his voyages: penguins use wings to paddle instead of fly
      snakes have rudimentary hind limbs
      the earth is very old
      islands had species that did not exist on the mainland

bones

    1. The image illustrates: vestigial structures
      homologous structures
      the fossil record
      natural selection
    2. Which of the following is an example of artificial selection: a panda’s thumb
      the breeding of dogs
      the galapagos finches
      a giraffe’s neck
    3. According to the theory of evolution by natural selection, which of the following is true: random mating is necessary for evolution to occur
      variation does not exist between members of the same species
      populations will change to better fit their environment
      individuals will adapt to their environment
    4. Which of the following are assumptions made with regards to the Theory of Evolution by Natural selection organisms compete with each other to survive
      variations exist among organisms
      not all organisms that are born survive to reproduce
      all of these

whale

    1. The image illustrates which of the following: artificial selection
      acquired characteristics
      homologous structures
      vestigial structures
    2. A panda’s thumb is considered an evolutionary contrivance because: it is assembled from wrist bones, and imperfect
      it is perfectly structured to grab leaves
      it is an structure that has no use
      none of these
    3. Which of the following outcomes would you predict for a population of bacteria exposed to a new antibiotic. over many generations, the bacteria would become resistant to the antibiotic
      over a few generations, the bacteria would evolve into Archaebacteria
      over a few generations, the bacteria would become extinct
      over many generations, the bacteria would become more susceptible to the antibiotic
    4. Which of the following is an example of convergent evolution: whales and sharks have similar body designs
      bees and hummingbirds have similar body designs
      bats and birds have similar body designs
      all of these
    5. Why is evolution called the “unifying theory of biology” because it explains the diversity of life on the planet
      because it serves as a model to predict how organisms will change
      it serves as a model to interpret relationships between organisms on the planet
      all of these

moths

  1. The image illustrates how peppered moths are related to other moths
    how peppered moths adapted to a changing environment
    how peppered moths became extinct
    how peppered moths became two species

Check Answers

Genetics Quiz

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Chromosomes & Genetics

1. A human being has _____ autosomes and ______ sex chromosomes
23, 1
22 pairs, 1 pair
23, 23
2, 2

2. A section of chromosomes that codes for a trait can be called a(n):
nucleotide
base-pair
gene
nucleus

3. Somatic cells of a human have ____ chromosomes and are called ____
10, haploid
92, diploid
23, haploid
46, diploid

4. A person who receives an extra chromosome, could have:
Heightened intelligence
Down Syndrome
Red eyes
Polygenic traits

5. Each chromosome consists of two identical:
genes
nuclei
chromatids
bases

6. If a person receives an X and a Y chromosome, that person is:
female
male
red eyed
mentally challenged

7. Two alleles for pea plant height are designated T (tall) and t (dwarf). These alleles are found on:
genes
sex chromosomes
ribosomes
homologous chromosomes

8. An animal has 40 chromosomes in its gametes, how many chromosomes would you expect to find in this animal’s brain cells?
1
20
40
80

9. A picture of a person’s chromosomes is called a(n):
karyotype
syndrome
chromatin
fingerprint

10. During which phase of mitosis is DNA replicated?
interphase
prophase
anaphase
telophase

Score =
Correct answers:

Introduction to Biology Quiz

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Introduction to Biology
 

1. Ultimately, all scientific knowledge comes from:
experimentation
observation
textbooks
both experimentation & observation

2. A hypothesis must be:
proven correct
testable
observed
experimental

3. A scientist testing the affects of a chemical on apple yeild sprays an orchard with the chemical. A second orchard does not receive the chemical. In the fall, the number of apples harvested from each forest is counted. Which of the following is the independent variable in the experiment?
the chemical
the number of apples
the first orchard
the second orchard

4. The orchard sprayed with the chemical yeilds an average of 60 apples per tree, the other orchard yields an average of 40 apples per tree. Based on the data, the scientist would:
report his data
test the chemical on other plants
determine that the chemical increases apple yield
determine that the results were inconclusive

5. In order for the apple tree experiment to be valid scientifically, both orchards must:
receive the same amount of sunlight
receive the same amount of water
have the same species of apple tree
all of these

6. Theories help scientists to:
explain large bodies of data
prove hypotheses
determine truth from lies
propose new ideas about how the world works

7. If a theory is challenged by new evidence, which of the following could occur?
the theory could be altered
the theory is accepted, not the evidence
the evidence is wrong
a vote is taken on whether to accept the new evidence

8. All living things must:
move
have two parents
eat food
maintain homeostasis

9. The mechanism by which evolution occurs is called:
creationism
natural selection
interdependence
metabolism

10. The smallest unit capable of carrying out life functions is:
a cell
tissue
DNA
blood

Score =
Correct answers: