STAT Quantitative Reasoning in Context 4 — Questions and Answers
Question 1: A bar chart shows monthly electricity usage: Jan 320 kWh, Feb 290 kWh, Mar 250 kWh, Apr 210 kWh. What is the average monthly usage over these four months?
- 267.5 kWh (Correct answer)
- 260 kWh
- 270 kWh
- 280 kWh
Correct answer: 267.5 kWh
(320 + 290 + 250 + 210) ÷ 4 = 1,070 ÷ 4 = 267.5 kWh.
Question 2: Two pipes fill a tank. Pipe A fills it in 6 hours, Pipe B in 4 hours. Working together, how long will they take to fill the tank?
- 2.4 hours (Correct answer)
- 3 hours
- 5 hours
- 2 hours
Correct answer: 2.4 hours
Combined rate = 1/6 + 1/4 = 5/12 tanks/hour; time = 12/5 = 2.4 hours.
Question 3: A jacket originally costs $180. It is discounted by 15%, and sales tax of 8% is then applied to the discounted price. What is the final cost?
- $165.24 (Correct answer)
- $162.00
- $163.80
- $167.40
Correct answer: $165.24
Discounted price = 180 × 0.85 = $153; after 8% tax = 153 × 1.08 = $165.24.
Question 4: A line graph shows a city's temperature rising from 5°C in January to 35°C in July, then returning to 5°C in December. Which statement is most accurate?
- The temperature change is approximately symmetric around July (Correct answer)
- The city is warmest in June
- The temperature increases faster in autumn than spring
- The annual mean temperature is 35°C
Correct answer: The temperature change is approximately symmetric around July
The description of rising from January to July and falling back to 5°C by December describes a roughly symmetric pattern.
Question 5: A data set has a mean of 50 and a standard deviation of 5. A score of 60 is how many standard deviations above the mean?
- 2 (Correct answer)
- 1.5
- 3
- 1
Correct answer: 2
(60 − 50) ÷ 5 = 10 ÷ 5 = 2 standard deviations.
Question 6: A pie chart shows a household's budget: housing 30%, food 25%, transport 15%, savings 20%, and other 10%. If the monthly income is $4,800, how much is spent on food and transport combined?
- $1,920 (Correct answer)
- $2,000
- $1,680
- $1,440
Correct answer: $1,920
Food + transport = 25% + 15% = 40%; 40% of $4,800 = $1,920.
Question 7: A school's test score data is: minimum 42, Q1 = 58, median = 70, Q3 = 82, maximum 95. What is the interquartile range (IQR)?
- 24 (Correct answer)
- 28
- 53
- 12
Correct answer: 24
IQR = Q3 − Q1 = 82 − 58 = 24.
STAT Quantitative Reasoning in Context 4
A bar chart shows monthly electricity usage: Jan 320 kWh, Feb 290 kWh, Mar 250 kWh, Apr 210 kWh.
What is the average monthly usage over these four months?