Question

A certain length measurement is performed 500 times. The mean value is 5.0m, and the standard deviation is 2cms. Assuming a normal distribution for the error in the measurement, how many readings fall within 5.15cm of the mean value

Answer 1

Using the normal distribution, it is found that 495 readings fall within 5.15cm of the mean value.

In a normal distribution with mean $\mu$ and standard deviation $\sigma$, the z-score of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

• It measures how many standard deviations the measure is from the mean.  
• After finding the z-score, we look at the z-score table and find the p-value associated with this z-score, which is the percentile of X.

In this problem:

• Mean of 5m, hence $\mu = 5$.
• Standard deviation of 2 cm, hence $\sigma = 0.02$

To find the proportion of readings that fall within 5.15cm of the mean value, first we need to find the following z-score:

$z = \frac{0.0515}{0.02}$

$z = 2.575$

The proportion is P(|z| < 2.575), which is the p-value of z = 2.575 subtracted by the p-value of z = -2.575.

Looking at the z-table, z = -2.575 has a p-value of 0.005, and z = 2.575 has a p-value of 0.995.

0.995 - 0.05 = 0.99

Out of 500 measurements:

(0.99)500 = 495

495 readings fall within 5.15cm of the mean value.

A similar problem is given at brainly.com/question/24663213