1) The population of bacteria doubles every 30 minutes.

2) At 3: 30 p.m. on Monday, the population was 240.

Quantity A	Quantity B
The bacteria population at 2 p.m. on Monday	40

A)The quantity in Column A is greater.
B)The quantity in Column B is greater.
C)The two quantities are equal.
D)The relationship cannot be determined from the information given.

KEY CONCEPT: If the population doubles every 30 minutes, then the population 30 minutes AGO was half the present population.

Let's create a table to keep track of times and populations.

TIME | POPULATION
3:30 | 240
3:00 | 120
2:30 | 60
2:00 | 30

So, we have:
Quantity A: 30
Quantity B: 40

Answer: B

Cheers,
Brent

Basically 240/2 = 120 this is at 3:00 PM

Then again divide by 2, yielding 60 at 2:30 PM

Then divide again by 2, we get 30 at 2:00 PM

30 < 40

Answer choice B

The population of bacteria doubles every 30 minutes. At 3:30 pm on Monday, the population was 240.

Quantity A	Quantity B
The bacteria population at 2:00 pm on Monday	40

A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.

This is a problem working backward

If the population was at 3.30 240 you have to halve it every half of one hour

At 2.00 was 30

B is the answer

As mentioned above the population doubles every 30 minutes, So that would be saying like it gets 2X every 30 minutes and 4X every hour
so we know that at 3:30 p.m. on Monday the population was 240 it and we have to find the population at 2:00 p.m. , So we can divide the number by 4 for every hour and by 2 for every half hour

Calculation :
240 -> 3:30 p.m.
for, 2:30 p.m. the value would be 240/4 = 60 so the bacteria quantity at 2:30 was 60
for, 2:00 p.m. the value would be 60/2 = 30

so the answer would be Quantity B > Quantity A