15.a Formula Logic

Question 1

What is a “formula logic” question?

Answer 1

The GMAT provides a formula and some hypothetical change to one or more of the measurements. They require you to logically analyze a change made to the formula.

Question 2

Solve:

Answer 2

Question 3

If you dont solve this algebraically, how else could you solve it?

Answer 3

Use a suitable replacement value and test!

Question 4

Solve:

Answer 4

This is using placeholder variables (r = 10, and r = 9). Could evidently also solve this algebraically.

Question 5

What does the phrase “factor of” mean?

Answer 5

Describes a hypothetical change to one or more of the measurements in the formula.

“The cylinder’s height is increased by a factor of 5”

Question 6

What does this mean:

“Increase 40 by a factor of 2”

Answer 6

40 x 2 = 80

Question 7

What does this mean:

“Increase 40 by a factor of 1/5”

Answer 7

40 + (40*0.2) = 40 + 8 = 48

Question 8

If X is increased by factor F, how would you express this?

(F is equal to or greater than 1)

Answer 8

XF

Question 9

If X is increased by factor F, how would you express this?

(F is smaller than 1)

Answer 9

X + (FX)

Question 10

If X is decreased by factor F, how would you express this?

(F is equal to or greater than 1)

Answer 10

X / F

Question 11

If X is decreased by factor F, how would you express this?

(F is smaller than 1)

Answer 11

X - XF

Question 12

80 is reduced by a factor of 1/4, what is the result?

Answer 12

80 - (80*0.25) = 80 - 20 = 60

Question 13

Solve:

Answer 13