let x be the number of 4s you that appear when you roll a di

let x be the number of 4\'s you that appear when you roll a die 5 times. determine e(x) and var(x)

Solution

when you roll a die 5 times
number of 4\'s you that appear = 1/6 = 0.1667
a)
Mean ( np ) =0.8335
b)
variance = npq = 5*0.1667*0.8333 = 0.6945
Standard Deviation ( npq )= 5*0.1667*0.8333 = 0.8334