120 hardness measurements are made on a large slab of steel with an average of rockwell c value of 39 and a standard deviation of 4.0. what percent of measurements should fall between 35 and 45?

77.45 %

Step-by-step explanation:

We assume that the measurements are normally distributed.

Given : Mean :

Standard deviation :

Let x be the randomly selected measurement.

Now we calculate z score for the normal distribution as :-

For x = 35, we have

For x = 45, we have

Now, the p-value =

In percent ,

Hence, the percent of measurements should fall between 35 and 45 = 77.45 %

i did it myself and i got 4.2 (b) hope its right

step-by-step explanation:

-2 is the right