High School

The weights of 1,000 men in a certain town follow a normal distribution with a mean of 150 pounds and a standard deviation of 15 pounds.

Calculate the probability that a randomly selected man weighs between 135 and 165 pounds.

Answer :

The weights of 1,000 men in a certain town follow a normal distribution with a mean of 150 pounds and a standard deviation of 15 pounds.

Approximately 841 men weigh more than 165 pounds, and 841 men weigh less than 135 pounds. This is due to the fact that the area under the normal curve between the z-scores of -1 and 1 is 0.8413, or 84.13%.

what is standard deviations ?

Standard deviation is a measure of how spread out a set of data is. It is calculated by taking the square root of the variance, which is the average of the squared differences from the mean. Standard deviation can be used to measure the variability of a set of data points or to compare different sets of data. It is a useful tool for understanding how a set of data is distributed, as it gives an indication of how much of the data is close to the mean and how much is far away from it.

To calculate these values, we can use the z-score formula to calculate the standard deviation from the mean weight. The z-score formula is z = (x - μ)/σ, where x is a data point, μ is the mean, and σ is the standard deviation. Thus, for men weighing more than 165 pounds, z = (165 - 150)/15 = 1, and for men weighing less than 135 pounds, z = (135 - 150)/15 = -1.

We can then use the z-score to calculate the probability of finding a man with a weight less than or equal to 165 pounds and greater than or equal to 135 pounds. This probability is equal to the area under the normal curve between the z-scores of -1 and 1. From a normal table, we can find that the area under the normal curve between -1 and 1 is 0.8413, which is equal to 84.13%.

Therefore, the number of men weighing more than 165 pounds is equal to 0.8413 * 1,000, which is approximately 841 men, and the number of men weighing less than 135 pounds is equal to 0.8413 * 1,000, which is also approximately 841 men.

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Complete questions as follows-

The weights of 1,000 men in a certain town follow a normal distribution with a mean of 150 pounds and a standard deviation of 15 pounds.

From the data, we can conclude that the number of men weighing more than 165 pounds is about , and the number of men weighing less than 135 pounds is about .