If your question is will he have enough money, the answer is no he will not.
To answer (a), we will need to find the Z value for 710 hours and 990 hours.


B) 68% of data lies between one standard deviation of the mean.
850 +70 = 920
850 - 70 = 780
.23(m)-12=35.
Think this is right. Haven't done these in a while
The answer is 10 ft. make a triangle 6ft tall, 8ft long (90 degrees to the other line) and draw a line to complete the triangle. This is a type of 3,4,5 triangle, a 6,8,10. The other way to do it is sqrt(6^2+8^2) = sqrt(36+64) = sqrt (100) = 10.
2/3 + (-1/3) = 2/3 - 1/3 = 1/3