Ms. johnson uses a statistics program to analyze all the data collected by her students during a lab experiment about the acceleration due to gravity. the program reports a mean of 31.5 and a standard deviation of 2.5. what is the variance of the data? round to the nearest tenth. a. 2.5 b. 5.6 c. 1.6 d. 6.3

The variance (σ^2) is the square of the differences between the mean and each data.
 The problem says that the program reports a mean of 31.5 and a standard deviation of 2.5, so you have to elevate the standar deviation to the power 2:

 σ^2 = (2.5)^2 
 σ^2 = 6.30       

 What is the variance of the data?
 The variance of the data is 6.30, so the the correct option is D.

Answer: r=4.5  feetexplanation: radius  r  is half of the diameter  d,⇒r=d2=92=4.5  feetidk i could be wrong