LSAT test scores are normally distributed with a mean of 155 and a standard deviation of 7. Find the probability that a randomly chosen test-taker will score 148 or lower.

Question

You may need to use the appropriate appendix table or technology to answer this question.

LSAT test scores are normally distributed with a mean of 155 and a standard deviation of 7. Find the probability that a randomly chosen test-taker will score 148 or lower. (Round your answer to four decimal places.)

Answer 1

that's one standard deviation below the mean

with the empirical rule we know 68% falls within 1 standard deviation from the mean. But that's both side of the mean. On the left side that means 50%-34% = 16% is below one standard deviation from the mean

answer: 16%

Or use z tables, found in statistics books or online.

look up z=-1, on the table, 1st column is 15.87, round to one decimal place =15.9%

or rounded to nearest integer: 16