X(4+ )=18x what is the missing number?

Wilma worker has a $90,000 insurance policy for which she pays $1,200 a year. to compare the cash value of the policy to investing the same amount of money at 6%, she performs the following calculations:

In the rectangle below ac=30 units what is de

Weekly wages at a certain factory are normally distributed with a mean of $400 and a standard deviation of $50. find the probability that a worker selected at random makes between $450 and $500