Martha estimated there were 90 marbles in a jar for a contest. the actual number of marbles in the jar was 112. what was the percent error of martha's estimation?

Logan wants to know how many skateboards have defective parts. he inspects 20,000 skateboards and keeps track of the number of defects per board. use his probability distribution table to find the expected value for defects on a skateboard.

Two times a number plus three times another number equals 4. three times the first number plus four times the other number is 7. find the numbers

Afrequency table of grades has five classes (a, b, c, d, f) with frequencies of 3, 13, 14, 5, and 3 respectively. using percentages, what are the relative frequencies of the five classes?