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A half-century ago, the mean height of women in a particular country in their 20s was 64.7 inches. Assume that the heights of

Ainat [17]

Answer:

99.5% of all samples of 21 of today's women in their 20's have mean heights of at least 65.86 inches.

Step-by-step explanation:

We are given that a half-century ago, the mean height of women in a particular country in their 20's was 64.7 inches. Assume that the heights of today's women in their 20's are approximately normally distributed with a standard deviation of 2.07 inches.

Also, a samples of 21 of today's women in their 20's have been taken.

Let $\bar X$ = sample mean heights

The z-score probability distribution for sample mean is given by;

Z = $\frac{\bar X -\mu}{\frac{\sigma}{\sqrt{n} } }$ ~ N(0,1)

where, $\mu$ = population mean height of women = 64.7 inches

$\sigma$ = standard deviation = 2.07 inches

The Z-score measures how many standard deviations the measure is away from the mean. After finding the Z-score, we look at the z-score table and find the p-value (area) associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X.

Now, Probability that the sample of 21 of today's women in their 20's have mean heights of at least 65.86 inches is given by = P( $\bar X$ $\geq$ 65.86 inches)

P( $\bar X$ $\geq$ 65.86 inches) = P( $\frac{\bar X -\mu}{\frac{\sigma}{\sqrt{n} } }$ $\geq$ $\frac{65.86-64.7}{\frac{2.07}{\sqrt{21} } }$ ) = P(Z $\geq$ -2.57) = P(Z $\leq$ 2.57)

= 0.99492 or 99.5%

The above probability is calculated by looking at the value of x = 2.57 in the z table which has an area of 0.99492.

Therefore, 99.5% of all samples of 21 of today's women in their 20's have mean heights of at least 65.86 inches.

3 0

3 years ago

SAT Math Question

mariarad [96]

I'm tentatively changing my answer to say this kind of relies on practical knowledge of how stores tend to operate. If 20 coupons are given out, the store has sold all 500 shirts, arguably at a loss to the retailer. They have to have more shirts in stock to be sold at full price because, well, that's how they make money. It's more likely that such a store would carry more than just 500 shirts at the start of each day, so A is (probably) wrong.

5 0

1 year ago

Find the probability of a student being 34 years old or younger. Express your answer as a percent

yarga [219]

Answer:

79%

Step-by-step explanation:

3 0

3 years ago

Eight more than three times the difference of four and a number” when n = 3?

Snezhnost [94]

8 + 3 (4 - n )
n= 3
8 + 3( 4-3)
8 + 3 * 1
8 + 3 = 11

8 0

3 years ago

Find the area use 3.14 for pi

Aleonysh [2.5K]

Answer:

15.14 cm^2

Step-by-step explanation:

Area of rectangle = 4cm x 3 cm = 12cm^2

Radius of the circle = 2 cm

Area of 1/4 of a circle = (pi x r^2) / 4

= (3.14 x 4) / 4 = 3.14 cm^2

3.14 cm^2 + 12cm^2 = 15.14 cm^2

5 0

2 years ago

Can I get help......​

Can I get help......