Mrs. Alberts has taught seventh grade math for thirty years. Every year she calculates and records the class average on the final exam. The following dot plot represents these average scores from the past thirty years.

Calculate the mean of the average scores and round this value to the nearest whole number. Then, calculate the mean absolute deviation of the scores (using the rounded mean) and round it to the nearest whole number, as well. Express your answer as a numerical value.
MAD=

How to use order of operation in 20 divide by 4 multiply 5 = 1

The management of a supermarket wants to adopt a new promotional policy of giving a free gift to every customer who spends more than a certain amount per visit at this supermarket. the expectation of the management is that after this promotional policy is advertised, the expenditures for all customers at this supermarket will be normally distributed with a mean of $95 and a standard deviation of $20. if the management wants to give free gifts to at most 10% of the customers, what should the amount be above which a customer would receive a free gift?

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?