Evaluate for a=-2,b=3,c=-12 and d=-4 ac/b-(a+d)

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

An elevator travels 310 feet in 10 seconds. at that speed, how far can't his elevator travel in 12 seconds?

Someone which statements are true? check all that apply.