Cognitive Reflection Test Rates, Ratios, and Proportional Traps

Question 1

If 4 machines take 4 hours to produce 4 units, how many hours will 8 machines take to produce 8 units?

Accepted Answer

4 hours

Answer

2 hours

Answer

8 hours

Answer

16 hours

Question 2

A car travels at 60 mph for the first half of a journey (by distance) and 40 mph for the second half. What is the average speed for the entire trip?

Accepted Answer

48 mph

Answer

50 mph

Answer

45 mph

Answer

52 mph

Question 3

A jacket is discounted by 20%, then discounted again by 25%. What is the total percentage reduction from the original price?

Accepted Answer

40%

Answer

45%

Answer

50%

Answer

35%

Question 4

Pipe A fills a tank in 6 hours and pipe B fills it in 3 hours. How long does it take with both pipes open simultaneously?

Accepted Answer

2 hours

Answer

4.5 hours

Answer

3 hours

Answer

1.5 hours

Question 5

A store increases a price by 25% and then decreases it by 25%. What is the net change in price?

Accepted Answer

6.25% decrease

Answer

No change

Answer

6.25% increase

Answer

12.5% decrease

Question 6

If it takes 3 workers 3 days to dig 3 holes, how many days does it take 1 worker to dig 1 hole?

Accepted Answer

3 days

Answer

1 day

Answer

9 days

Answer

6 days

Question 7

A number is increased by 50% and then decreased by 50%. What is the net result compared to the original?

Accepted Answer

25% decrease

Answer

Equal to the original

Answer

25% increase

Answer

No change