It’s math homework

55869 Assignment
X- length is N(19.3, 1.1)
P(X<21.7) = P(Z<
=0.985439
X is N(13.1, 2.2)
P(X>19) = P(Z>(19-13.1)/2.2) = P(Z>2.6818)
=1-F(2.6818) = 1-0.9963 = 0.0037
X is N(73,7.5)
a) P(X>78) = P(
=1-F(0.6667) = 0.2525
b) For mean score of 20 students std deviation would be= 6.5/sqrt 7.5 = 2.3735
Hence x bar is N(73, 2.3735)
P(X bar >78) = P(Z>(78-73)/2.3735) = P(Z>0.9824) = 0.0176
c) P(68