In the following practice questions, you start with a simple problem of pinpointing when a runner twisted her ankle, based on a bar graph of her running times. The second question gets trickier, and you're asked to figure out how much a student needs to improve her marks in one class to raise her overall average by a certain amount.

## Practice questions

- Alice was trying to explain how the length of time she could run each morning had improved each month since she started, except for the month she twisted her ankle. She drew the following graph to show her friends Mary and Kevin the average length of time (in minutes) she ran each day each month:
In which month did Alice likely twist her ankle?

**A.**June**B.**February**C.**August**D.**September - Leonora has just received her mid-term report card. Her grades are as follows:
Leonora's average grade is 77.8 percent. To get into the college of her choice, she needs an average of 80 percent. English is her best subject. By how many percentage points will her English score have to go up, assuming all her other subjects stay the same, to get into college?

**A.**8**B.**9**C.**10**D.**11

## Answers and explanations

**The correct answer is Choice (A).**Alice has converted her story into a graph, and you're being asked to interpret the line graph in conjunction with her story. Because her average daily time had been increasing until May, dropped in June, and recovered in July and August, you can assume that the twisted ankle slowed her down. It likely happened in June.

**The correct answer is Choice (D).**This question involves data analysis. You're asked to apply measures of central tendency (the mean) and analyze the effect of changes in data on this measure. If Leonora's present average is 77.8 percent and she wants to get an average of 80 percent, she needs enough marks to get an additional 2.2 percent (80 – 77.8).

Because Leonora is taking five subjects, she requires 5 extra points for each percent increase. Thus, she requires (2.2)(5) = 11 additional points. The problem says that English is her best subject, so she would need the 11 extra points in English.