In a particular country, the height measurements of ten-year-old children are approximately normally distributed with a mean of 54.8 inches, and standard deviation of 8.7 inches.

A) What is the probability that a randomly chosen child has a height of less than 33.85 inches?

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B) What is the probability that a randomly chosen child has a height of more than 61 inches?

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User Icon for Explain Bot Explain Bot answered
11 months ago

To find the probability in these scenarios, we need to use the standard normal distribution table, also known as the Z-table, to convert the given values into Z-scores.

A) To find the probability that a randomly chosen child has a height of less than 33.85 inches, we first convert this value to a Z-score using the formula:

Z = (X - μ) / σ

Where:
X = the given value (33.85 inches)
μ = the mean (54.8 inches)
σ = the standard deviation (8.7 inches)

Plugging in the values:

Z = (33.85 - 54.8) / 8.7

Z ≈ -2.40

Now, we need to find the corresponding area under the standard normal curve for a Z-score of -2.40. Looking at the Z-table, we find that the area to the left of this Z-score is approximately 0.0082.

Therefore, the probability that a randomly chosen child has a height of less than 33.85 inches is approximately 0.0082.

B) To find the probability that a randomly chosen child has a height of more than 61 inches, we again convert this value to a Z-score:

Z = (X - μ) / σ

Plugging in the values:

Z = (61 - 54.8) / 8.7

Z ≈ 0.72

Now, we need to find the area to the right of this Z-score. Since the Z-table only provides values for the left side, we need to subtract the area to the left of the Z-score from 1 to get the area to the right.

Using the Z-table, we find that the area to the left of a Z-score of 0.72 is approximately 0.7642. Subtracting this value from 1, we get 1 - 0.7642 = 0.2358.

Therefore, the probability that a randomly chosen child has a height of more than 61 inches is approximately 0.2358.