Thread: problem of normal distribution

i set up the equation P[ (X1+X2+...+X5)/5 < K ] = 0.3
then P[ z < ( 5K-(20)(5) )/ √(4)(5)] = 0.3
am i right???
if i am wrong, show me how to solve it please...

Originally Posted by kin

i set up the equation P[ (X1+X2+...+X5)/5 < K ] = 0.3
then P[ z < ( 5K-(20)(5) )/ √(4)(5)] = 0.3
am i right???
if i am wrong, show me how to solve it please...

Note that ~ Normal .

So .

So, although it's a bit hard to tell, it looks like you're right.