A random sample of 81 automobiles traveling on a section of an interstate showed an average speed of 60 mph. The distribution of speeds of all cars on this section of highway is normally distributed, with a standard deviation of 13.5 mph.

1. If we are interested in determining an interval estimate for ? at 86.9% confidence, the z value to use is

a. 1.96
b. 1.31
c. 1.51
d. 2.00

2. The value to use for the standard error of the mean is

a. 13.5
b. 9
c. 2.26
d. 1.5

that is the sum

step-by-step explanation:

there are no other answers without knowing the variables values

x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

step-by-step explanation:

last month maria hiked the 5-mile mountain trail a number of times and she hiked the 10-mile canal trail several times. let x represent the number of times she hiked the 5-mile trail, and let y represent the number of times she hiked the 10-mile trail. if she hiked a total of 90 miles, which equation can be used to find the number of times maria hiked each trail? x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

idk

step-by-step explanation: