We want the integral of the standard normal from -z to z to be 0.85. Let's look at some standard normal tables and pick the right one.
It's easy to find the Erf one, which is the integral of the unit normal from 0 to z. That will be exactly half of the integral from -z to z. So we look for the z value corresponding to a probability of 0.425 in that table and find
z = 1.44
Answer: 1.44
[figure from Wikipedia]
Answer:
168 miles
Step-by-step explanation:
If he uses 5 gallons to drive 140 miles, that means that he can drive 24 miles for every gallon (140/5=24)
7 times 24 is 168 so he can drive 168 miles on 7 gallons of gas
Answer: 6 4/5 pounds
Step-by-step explanation: