If a, b,c are non-zero real numbers and a+b+c=0 then prove that a2/bc+ b2/ac+c2/ab=3

For the equations below which statement is true ?

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

Asinusoidal function whose frequency is 1/6pi