Answer
a. $-2.28$
b. $-0.92$
c. $-0.27$
Work Step by Step
a. 98.87% of the area under the distribution curve lies to the right of it.
The area to the left would be $1-0.9887=0.0113$ which corresponds to a z value of $-2.28$
b. 82.12% of the area under the distribution curve lies to the right of it.
The area to the left would be $1-0.8212=0.1788$ which corresponds to a z value of $-0.92$
c. 60.64% of the area under the distribution curve lies to the right of it.
The area to the left would be $1-0.6064=0.3936$ which corresponds to a z value of $-0.27$
