**Question 81 – “Ada and Paul…”**

OG Explanation is fine. Alternatively,

**Question 82 – “Three business partners, **

OG Explanation is fine.

**Question 83 – “Which of the…” **

OG Explanation is fine.

**Question 84 – “The average (arithmetic mean…”**

OG Explanation is fine. Sum of the 6 values is 6(8.5) = 51. The sum of the 5 values is 5(7.2) = 36. Thus 51-36=15

**Question 85 – “In the rectangular….”**

OG Explanation is fine.

**Question 86 – “What is the largest…”**

OG Explanation is fine.

**Question 87 – “One inlet…”**

OG Explanation is fine. Alternatively, we could pick numbers. Suppose the capacity was 15 (say gallons) then the first pipe would fill at a rate of 3 gallons per hours. The Second pipe would fill at rate of 5 gallons per hour. Combined they would fill at a rate of 8 gallons per hours. The job is 15 gallons so two-thirds of the job is 10 gallons. If it fills at 8 gallons per hour, it takes 1.25 or 5/4 hour to fill up 10 gallons. The answer is C.

**Question 88 – “(1/5)….”**

OG Explanation is fine.

**Question 89 – “If the length…”**

OG Explanation is fine. Alternatively, we could just pick numbers. Suppose the length and width were both 10 meters. The new length and width would be 12 meters.

Old Area = 10(10) = 100

New Area = 12(12) = 144

Percent Increase: 44%

The Answer is E

**Question 90 – “The population….”**

OG Explanation is fine. Alternatively, the population increases 500 times. 2^{9} = 512 which is approximately 500. Each interval the population doubles is 2 minutes and the population must double 9 times, so it will take about 18 minutes for the population to grow from 1,000 to 500,000.

An answer from an expert! Thanks for contirubting.