Unit 8 · Test

Unit 8 test: Statistics

15 questions. Answer them all, then submit to see your score. Solutions unlock after you submit.

This test covers populations and samples, random sampling and bias, making inferences from samples, sampling variability, and comparing two populations using center and spread.

Question 1

A news station wants to know how the $50{,}000$ adults in a city feel about a new stadium. It calls $400$ adults. What is the sample?

Question 2

A teacher wants to choose $5$ of her $30$ students at random to test a new computer game. Which method gives a random sample?

Question 3

To estimate how many hours per week people in a town exercise, Priya surveys people as they leave a fitness center. How will this likely affect her results?

Question 4

A school has $270$ sixth graders, $240$ seventh graders and $210$ eighth graders. The principal wants a sample of $108$ students with each grade represented in proportion to its size. How many seventh graders should be in the sample?

Enter a number. Fractions like 3/4 and sqrt(2) are OK.

Question 5

A middle school has $640$ students. In a random sample of $40$ students, $13$ said they play on a sports team. Estimate how many students in the school play on a sports team.

Enter a number. Fractions like 3/4 and sqrt(2) are OK.

Question 6

In a random sample of $80$ voters, $20$ said they plan to vote for a new park. Based on this sample, what percent of all voters plan to vote for the park?

Enter a number. Fractions like 3/4 and sqrt(2) are OK.

Question 7

A random sample of $6$ students reported how many hours they spent on homework last week: $4, 9, 6, 5, 8, 7$ . Estimate the mean number of hours spent on homework for all students. Round to the nearest tenth if needed.

Enter a number. Fractions like 3/4 and sqrt(2) are OK.

Question 8

A factory randomly selects $120$ phone chargers from a batch of $3{,}000$ and finds $3$ defective chargers. Estimate the number of defective chargers in the whole batch.

Enter a number. Fractions like 3/4 and sqrt(2) are OK.

Question 9

Five students each took a random sample of $20$ people from the same town and found the fraction who own a bike: $0.40$ , $0.50$ , $0.45$ , $0.35$ , $0.50$ . Which statement is true?

Question 10

A ranger catches $80$ deer in a forest, tags them, and releases them. Later she observes $60$ deer at random and finds that $12$ of them have tags. Estimate the number of deer in the forest.

Enter a number. Fractions like 3/4 and sqrt(2) are OK.

Question 11

Find the mean absolute deviation (MAD) of the data set: $3, 5, 6, 7, 9$ .

Enter a number. Fractions like 3/4 and sqrt(2) are OK.

Question 12

The dot plot shows how many books each of $10$ students read over the summer. What is the mean number of books?

Enter a number. Fractions like 3/4 and sqrt(2) are OK.

Question 13

The ages of $7$ members of a chess club and $7$ members of a robotics club are listed below. How many years greater is the median age of the chess club than the median age of the robotics club?

Chess club: $34, 19, 52, 27, 41, 23, 60$
Robotics club: $15, 22, 18, 30, 14, 20, 17$

Enter a number. Fractions like 3/4 and sqrt(2) are OK.

Question 14

Random samples of two breeds of dog were weighed. Breed A had a mean weight of $24$ kilograms and Breed B had a mean weight of $33$ kilograms. Both samples had a MAD of $3$ kilograms. How many MADs apart are the two means?

Enter a number. Fractions like 3/4 and sqrt(2) are OK.

Question 15

Random samples of plants grown with Fertilizer X and with Fertilizer Y were measured after a month. The Fertilizer X sample had a mean height of $30$ cm and the Fertilizer Y sample had a mean height of $31$ cm. Both had a MAD of $5$ cm. Which conclusion is best?