Ch 6 FDP Strategies

Question 1

List the DS Process - Step 1 and 2 ** The key to DS is to remember that it does not require you to answer the question asked in the question stem. Instead, you need to decide whether the statements provide enough info to answer the question. ** DS tests logical reasoning as much as mathematical concepts.

Answer 1

Step 1: Separate additional info from actual question.

Step 2: Determine whether the question is Value or Yes/No Value: If the question asks for unknown value, there can only be 1 possible value. If there are more than 1 possible value, the stmt is insufficient. Yes/No: Suff stmt will provide a definite YES or definite NO. Stmt that provides Could be Yes/No, is insuff

Sufficient Not Sufficient

Value: 1 value More than 1 value

Yes/NO: 1 Ans (Yes/No) More than 1 And (Y and N)

Question 2

List the DS Process - Step 3 and 4

Answer 2

Step 3: Decide exactly what the question is asking

Ask yourself 2 questions: 1) What, precisely would be sufficient? 2) What, precisely would not be sufficient?

Step 4: Use the Grid to evaluate the statements. AD BCE

Question 3

Give examples of Concrete Values vs. Relative Value when working in DS

Answer 3

Concrete Value - are actual amounts (# of tickets sold, liters of water etc). Need more info to find concrete value.

Relative Value - relate two quantities using fraction, decimals, percents, ratios (twice as many, 60% less, ratio of 2:3 etc). Relative values are intimately related to ratios.

Question 4

DS Relative Value fact

Answer 4

If a DS question asks for the relative value of two pieces of a ratio, ANY statements that gives the relative value of ANY two pieces of the ratio will be sufficient.

Question 5

DS Fact

Answer 5

If a DS question asks for the concrete value of one element of a ratio, you will need BOTH the concrete value of another element of the ratio AND relative value of two elements of the ratio.

Question 6

Smart Numbers: Multiplies of the Den

Q: The Crandall’s hot tub is 1/2 filled. Their swimming pool which has a capacity four times that of the tub, is filled to the 4/5 of its capacity. If the hot tub is drained into the swimming pool, to what fraction of its capacity will the pool be filled?

Answer 6

Sometimes, fraction problems on the GMAT include unspecified numerical amounts; often unspecified amounts are described by variables. In these cases, pick real numbers to stand in for the variables. To make the computation easier, choose SMART Numbers equal to common multiples of the den of the fraction.

Ex- hot tub and swimming pool where hot tub is 1/2 filled and pool is 4/5 of its capacity. In this ex since there are no real numbers given, get the least common den by using the fractions given in the question. In this question, common den is 2*5 = 10. So 10 is your SMART #.

** Hot Tub** ** Swimming Pool**

Total Capacity: 10 units 10 units* 4(capacity)= 40 units

Filled: 1/2* 10 units= 5 4/5*40= 32 units

Adding 5 units of hot tub to 32 units of pool = 37. 37 unis of water and a total capacity of 40, the pool will be filled 37/40 of its total capacity.

Question 7

Mark’s comic books collection contain 1/3 Killer Fish comics and 3/8 Shazaam woman critics. The remainder of his collection consists of Boom comics. If Mark has 70 Boom comics, how many comics does he have in his entire collection?

** DO Pick SMART numbers when no amounts are given, but DO NOT pick SMART numbers when ANY amount or total is given

Answer 7

** When Not to Use Smart Number.

In this question, we know a piece of the total which is 70 Boom comics so we have to use this info to get the other info.

Therefore, don’t use Smart #

1/3 Killer Fish + 3/8 Shazaam Woman= 17/24 comics that are NOT Boom. 24-17=7 Therefore, 7/24 of the comics are Boom 7/24x=70 x=70*24/7 x=240

Question 8

A shirt that initially cost d dollars was on sale for 20% off. If s represent the sale price of the shirt, d is what % of s?

SMART #: Pick 100

The fastest way to success with GMAT percent problems with unspecified amount is to pick 100. So pick 100 for the original price of the shirt.

Answer 8

Initial cost = d = 100

Sale = s = 20% discount = 80

d is what % of s?

100 = x/100(80)

100 = 4x/5

x = 100*5/4

x = 125

Question 9

Karen bought a new television, originally priced at 690. However, she had a coupon that saved her 67. For what % discount was Karen’s coupon?

Answer 9

Use Benchmark Values: 10%.

Since 10% of 690 is 69. Therefore, 67 is slightly less than 10% of 690.

To find 10% of any #, just move the decimal point to the left one place

Ex- 10% of 500=50

10% of 34.99= 3.499

Question 10

What is 1,530,794/(31.49*10⁴)

Answer 10

The heavy division shortcut to save time on the exam.

Step 1: Set up the division problem in the fraction form: 1,530,794/31.49*10⁴

Step 2: Rewrite the problem, eliminating power of 10: 1,530,794/314,900

Step 3: Get single digit to the left of the decimal in the den and num. 1,530,794/314,900= 15.30794/3.14900

Step 4: 15/3= 5 Approx ans is 5. This is shortcut

Question 11

Translate: There are 40% more women than men

There are 30% more cherries than apples

Answer 11

1.4m=w

c=1.3a

In questions like this, first set up equation that list both variances. ex: a=c. Question says that there are 30% more cherries so how can you balance the equation so both sides are equal if there are 30% more cherries on one side of the equation.

You have to multiply apples by 1.3 so you get the equation to balance. Therefore: c=1.3a. So if you multiply apples by 1.3, the equation will equal cherries.