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Given that x is a normal variable with mean = 49 and

standard deviation = 6.9, find the following probabilities.
(a) P(x ≤ 60)

1 Answer

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Final answer:

To find the probability P(x ≤ 60) for a normal variable with mean 49 and standard deviation 6.9, calculate the z-score for x = 60 and use a standard normal distribution table or calculator to find the associated probability.

Step-by-step explanation:

To find the probability P(x ≤ 60), we need to calculate the area under the normal distribution curve up to the value of 60.

Since the given variable x is normally distributed with a mean of 49 and a standard deviation of 6.9, we can find the z-score for x = 60 using the formula:

z = (x - mean) / standard deviation

Substituting the values, we get:

z = (60 - 49) / 6.9 = 1.59

Now, we can use a standard normal distribution table or a calculator to find the probability associated with the z-score of 1.59. The probability P(x ≤ 60) is equivalent to the probability of z ≤ 1.59.

Using a standard normal distribution table or calculator, we find that the probability P(x ≤ 60) is approximately 0.9441, or 94.41%.

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