The random sample size is .

of adult americians had obtained bacheors degree, thus .

The value of .

The value of mean is .

Substitute and .

The value is .

The standard deviation is .

Substitute , and .

.

The standard deviation is .

Find the probability .

.

Find the corresponding -values for and .

The value of is .

For , and

.

For , and .

.

The approximate area corresponds to is .

Therefore, the probability that in a random sample of people , between is .

The probability that in a random sample of people , between is .

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