AP Statistics 4.7.D Standard Error for Two Means

Practise calculating the standard error of a difference between independent sample means by combining the two variance-over-sample-size terms.

Exam points

Compute sqrt(s1 squared/n1 + s2 squared/n2), keeping variances additive for independent samples.

[Maximum number: 1]

In a 95 percent confidence interval,which of the following is the standard error of the difference of the two sample means between all comedy movie downloads and all drama movie downloads from the streaming service?

$\sqrt{\frac{113^{2}}{32}+\frac{141^{2}}{41}}$

$\sqrt{\frac{113^{2}}{32}-\frac{141^{2}}{41}}$

$\sqrt{\frac{113^{2}+141^{2}}{32+41}}$

$\sqrt{\frac{113^{2}-141^{2}}{32+41}}$

$\frac{113}{\sqrt{32}}+\frac{141}{\sqrt{41}}$ In a certain restaurant, 70 percent of the customers order a drink other than water and 44 percent of the customers order dessert. Of the customers who order a drink than water, 58 percent order dessert.

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4.7.D—Calculate the standard error and margin of error for estimating the difference between two population means question 1