Question

The GMAC Insurance company reported that the mean score on the National Drivers Test was 69.9 with a standard deviation of 3.7 points. The test scores are approximately bell-shaped. Approximately 68% of all test scores were between two values A and B. What is the value of A? Write only a number as your answer. Round to one decimal place.

Answer 1

66.2

Explanation:

We know that the middle 68% of the distribution is between -1 and +1 standard deviations from the mean. -1 standard deviation is a score of ...

69.9 - 3.7 = 66.2

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Comment on the question

The way the question is worded, "A" can be any value less than 68.1, down to -∞. The question does does not require the A-B range to be symmetrical.