Question 1133709
1. z<=(x-mean)/sd or <=(990-1016)/268 or -26/268 or -0.10. Assume the sd is known as a population since the sample sd is not given.
probability z is less than that is 0.4602

2. z<=(x-mean)/sigma/sqrt(n), assuming the sd is known as a population.
z<=(990-1016)/268/sqrt(61)
z<=(-26*sqrt(61))/268 or -0.76. I use z to two decimal places
that probability is 0.2236