Question

What is the probability that a random sample of 12 second grade students results in a mean reading rate of more than 95 words per minute?

Answer 1

The probability that a random sample of 12 second grade students results in a mean reading rate of more than 95 words per minute is 0.4582.

Given that the population mean, $\mu$ = 90 wpm

The standard deviation of the population ,$\sigma$ = 10

Sample size, n = 12

Sample mean, $\bar x$ = 95

The reading rate of students follows the normal distribution.

Let z = $\frac{\bar x - \mu}{\frac{\sigma}{\sqrt n} }$

        = $\frac{95 - 90}{\frac{10}{\sqrt 12} }$

        = 1.732

Probability that the mean reading exceeds 95 wpm = P($\bar x$ >95)

                                                                                       = P(z>1.732)

                                                                                       = 1- P(z<1.732)

                                                                                       = 0.4582

[The value 0.4582 found from the area under the normal curve using tables].

Learn more about Normal Distribution at brainly.com/question/27701525

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