Math  /  Data & Statistics

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Student loans: The Institute for College Access and Success reported that 65%65 \% of college students in a recent year graduated with student loan debt. A random sample of 90 graduates is drawn. Round your answers to at least four decimal places if necessary.
Part 1 of 6 (a) Find the mean μp^\mu_{\hat{p}}.
The mean μp^\mu_{\hat{p}} is 0.65 .
Part 2 of 6 (b) Find the standard deviation σp^\sigma \hat{p}.
The standard deviation σp^\sigma_{\hat{p}} is 0.0503 . pp
Part: 2/62 / 6
Part 3 of 6 (c) Find the probability that less than 52%52 \% of the people in the sample were in debt.
The probability that less than 52%52 \% of the people in the sample were in debt is \square . Skip Part Check Save For Later Submit A Q 2024 McGraw Hill LLC All Rights Reserved. Terms of Uso - Fivacy Center

Studdy Solution

STEP 1

What is this asking? We're looking at the probability that less than 52% of a group of 90 recent graduates have student loan debt, knowing that 65% of all graduates typically do. Watch out! Don't forget to convert percentages to decimals before calculating, and make sure to use the sample size correctly in your calculations!

STEP 2

1. Calculate the z-score.
2. Find the probability associated with the z-score.

STEP 3

We're interested in the probability that *less* than 52% of the sample has debt.
So our **target proportion** is 0.520.52.

STEP 4

From the problem, we know the **mean** proportion of graduates with debt is μp^=0.65\mu_{\hat{p}} = 0.65, and the **standard deviation** is σp^=0.0503\sigma_{\hat{p}} = 0.0503.

STEP 5

The z-score tells us how many standard deviations our **target proportion** is away from the **mean**.
The formula is: z=target proportionmeanstandard deviation z = \frac{\text{target proportion} - \text{mean}}{\text{standard deviation}} Plugging in our values: z=0.520.650.0503 z = \frac{0.52 - 0.65}{0.0503} z=0.130.0503 z = \frac{-0.13}{0.0503} z2.58 z \approx -2.58 So our **z-score** is approximately 2.58-2.58.
This means our **target proportion** of 0.520.52 is 2.582.58 standard deviations *below* the **mean** of 0.650.65.

STEP 6

A z-score of 2.58-2.58 corresponds to a probability.
We can look this up in a z-table (negative z-scores are usually in a separate table) or use a calculator with a built-in z-score function.

STEP 7

Looking up 2.58-2.58 in the z-table, we find a probability of approximately 0.00490.0049.
This is the probability of getting a sample with a proportion of graduates in debt less than 0.520.52.

STEP 8

The probability that less than 52% of the people in the sample were in debt is approximately 0.00490.0049.

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