Number 3 is the one i need with

Ngrid mixes 3.6 pounds of almonds with some raisins to make a trail mix. she divides the trail mix into 12 equal portions. each portion weighs 0.7 pound. how many pounds of raisins did she use to make the trail mix? express the answer to the nearest tenth.

The number of potato chips in a bag is normally distributed with a mean of 71 and a standard deviation of 2. approximately what percent of bags contain between 69 and 73 potato chips? approximately 68% approximately 71% approximately 95% approximately 99.7%

On a string instrument, the length of a string varies inversely as the frequency of its vibrations. an 11-inch string has a frequency of 400 cylces per second. find the frequency of a 10-icnch string.