【官方】SAT数学每日一题附答案和解析(2018年2月26日)

Mathematics>Standard Multiple Choice

Read the following SAT test question and thenclick on a button to select your answer.

A potato chip company produces the same numberof snack-sized bags of potato chips every month. Amanager at the company randomly selects a sample of snack-sized bags of potato chips to beweighed in a routine quality-assurance check each month. The January sample had a meanweight of 0.95 ounces and a margin of error of 0.06 ounces. The February sample had a meanweight of 0.98 ounces and a margin of error of 0.04 ounces. Based on these findings, which ofthe following is an appropriate conclusion?

A.Most of the snack-sized bags of potato chips produced by the company in January each had aweight of at least 0.95 ounces, while most of the snack-sized bags of potato chips produced bythe company in February each had a weight of at least 0.98 ounces.

B.The mean weight of all the snack-sized bags of potato chips produced by the company inJanuary must have been 0.03 ounces more than the mean weight of all the snack-sized bags ofpotato chips produced by the company in February.

C.The mean weight of all the snack-sized bags of potato chips produced by the company inJanuary was 0.03 ounces less than the mean weight of all the snack-sized bags of potato chipsproduced by the company in February.

D.The number of snack-sized bags of potato chips in the January sample was less than thenumber of snack-sized bags of potato chips in the February sample.

答案：D

解析：

Choice D is correct. Start by interpreting the resultsof each sample individually before comparing thetwo.

The January sample had a mean weight of 0.95 ounces and a margin of error of 0.06 ounces. The February sample had a mean weight of 0.98 ounces and a margin of error of 0.04 ounces.

This means that the average weight of a snack-sized bag of potato chips in the January samplewas less than the average weight of a snack-sized bag of potato chips in the February sampleand that the margin of error for the January sample was larger than the margin of error forthe February sample.

The weight of the samples does not mean that the entire populations had the same attributes, but the margin of error does give some insight about the sample sizes.

Since the population of all snack-sized bags of potato chips was the same in January as it wasin February, the larger margin of error in January indicates that the January sample size wassmaller than the February sample size.