STAT Scientific and Mathematical Reasoning 2

Question 1

A scientist measures the pH of a solution and finds it is 4. She then dilutes the solution 10-fold with pure water. Assuming complete mixing, what is the new approximate pH?

Accepted Answer

5

Answer

Diluting 10-fold reduces H⁺ concentration by a factor of 10, raising pH by approximately 1 unit from 4 to 5.

Question 2

In a controlled experiment, plants in Group A are watered daily and given fertilizer, while plants in Group B are watered daily but given no fertilizer. Plants in Group C receive neither water nor fertilizer. What is the purpose of Group B?

Accepted Answer

It acts as a control to isolate the effect of fertilizer

Answer

Group B controls for watering so any difference between A and B can be attributed solely to fertilizer.

Question 3

A graph shows a straight line passing through the origin with a steep positive slope. Which relationship does this best represent?

Accepted Answer

Direct proportionality with a large constant

Answer

A straight line through the origin indicates direct proportionality (y = kx), and a steep slope means k is large.

Question 4

A car travels 240 km in 3 hours, then 180 km in 2 hours. What is the car's average speed for the entire journey?

Accepted Answer

90 km/h

Answer

Total distance = 420 km, total time = 5 hours; average speed = 420 ÷ 5 = 84 km/h — wait, that's 84. Recalculating: 240+180=420, 3+2=5, 420/5=84 km/h.

Question 5

Two identical metal spheres, one charged with +6 μC and one with −2 μC, are briefly touched together and then separated. What is the charge on each sphere after separation?

Accepted Answer

+2 μC each

Answer

Total charge = +6 + (−2) = +4 μC; shared equally between identical spheres gives +2 μC each.

STAT - Special Tertiary Admissions Test Practice Test

STAT - Special Tertiary Admissions Test Practice Test

STAT Scientific and Mathematical Reasoning 2