Set up the problem like a ratio by using fractions.
Step-by-step explanation:
For every 3oz it costs $10, and you're trying to find out the amount you can get for $15.
If you set up 3/10 = x/15, you can solve for x by multiplying 3 and 15 together, giving you 45. After that, you divide 45 by 10 and you will get the answer 4.5
According to the 68-95-99.7 rule, 95% of the data is comprised within two standard deviations of the mean (39-20 to 39+20 months), while 99.7% of the data is comprised within two standard deviations of the mean (39-30 to 39+30 months).
Therefore, the percentage of cars still in service from 59 to 69 months is:
The approximate percentage of cars that remain in service between 59 and 69 months is 2.35%.