Foundation
28th June 2025
- 1Percentiles
A data set of 50 exam scores has the 20th percentile at 42 marks and the 80th percentile at 78 marks. Explain what these two values tell you about the middle 60% of scores.
- 2Crude Rate and Rates of Change
A population falls from 8,000 to 7,600. Find the percentage rate of change, stating whether it is an increase or decrease.
- 3Spearman's Rank Interpretation
A researcher finds rs = 0.99 between a town's number of ice cream vans and its number of sunburn cases, and concludes the vans cause sunburn. Explain why this conclusion may be wrong.
- 4Conditional Probability (Foundation)
A drawer has 7 black socks and 5 white socks. Two socks are taken without replacement. Find P(second sock is black given the first sock was black).
- 5Estimating from Samples (Foundation)
A survey of 30 shoppers out of 900 in a store found the mean amount spent was 18.50 pounds. What is the best estimate of the mean amount spent by all 900 shoppers?
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