A candidate for mayor wants to know how strong her support is among voters, so she posts an online survey on her campaign website for voters to take.
Is this sample of voters likely to be biased or unbiased? A. biased B. unbiased

To determine whether voters would be willing to vote for a tax increase to improve the city’s schools, the board of education surveys 500 parents of children in the city’s schools.
Why is this sample likely to be biased? A. The entire population of the city was not surveyed. B. Parents of school children are too busy to be bothered with surveys. C. There are not enough people in the sample. D. Parents of school children are more likely to be willing to pay more to improve schools.

In a bin containing 500 marbles, 180 are red, 240 are blue, and 80 are green. In a bowl of 25 marbles scooped from this bin, how many would be expected to be green? A. 4 B. 8 C. 9 D. 12

A battery manufacturer randomly tests 500 batteries and finds that 3 are defective.
How many defective batteries would be expected in a shipment of 12,000 batteries? A. 120 B. 72 C. 60 D. 36

A large bin of mixed nuts contains peanuts, cashews, almonds, and walnuts. Sheila scoops out a bowl full of nuts and counts how many of each type she has: 17 peanuts, 9 cashews, 12 almonds, and 10 walnuts.
Armando scoops out a bowl of 32 nuts. About how many should he expect to be cashews? A. 5 B. 6 C. 9 D. 18

1) A. Biased because the population could be uneven. Too many of one ethnicity, too many of one gender, etc.

2) I believe this one is C. because there are not enough people. You need to survey the majority of parents instead of a selected few.

3) There are 80 green marbles per 500, therefore calculate the percentage. $$\frac{80}{500}=0.16$$ or $$16$$ percent. Multiply $$16$$ percent or $$0.16$$ times 25. It gives you $$4$$.

4) This one is a probability thing too. For every 500 batteries, there are 3 that are defective, therefore, $$\frac{3}{500}= 0.006$$.

$$0.006*12000 = 72$$

5) Yet another one. Add up all the nuts and you get $$48$$. The chance of getting a cashew from these $$48$$ is: $$\frac{9}{48}=0.1875$$.

Therefore: $$0.1875*32=6$$

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