If a stationery store owner buys 50% more identically-priced calendars

Hi,
This is a Algebra question,
There are two ways to solve most of the Algebra question in GMAT.
1. Normal equation way.
2. Plugging in/ Back-Solving.
1. Normal Equation way:
This is like your school math; assume variables for the unknown quantities in the question.
Also try to keep variables minimal.
Here in this question,
Let “x” the usual price of each calendar and “n” be the usual number of purchase,
Question says, 20 percent discount given on the usual price and 50 percent more number of calendars purchased.

Price No. of Items
“x” “n"
0.8x 1.5n

From the question,
120 * x = (0.8x)*(1.5n)
So n = 100
So that’s it, you just need to form the equation and find a relation given in the question.
In 30 seconds, if you are not able to construct the equation then think about the alternate way.

2. BackSolving:
Whenever it’s a equation type question, we can also use the answer choices and work backwards rather than solving it using equations.
Always start with answer choice “C”, because answer choices will be in order in GMAT.
Here the answer choice C is 100.
That is it means to usually hundred calendars purchased,
Let’s check whether it matches condition given in the question,

Price No. of Items

“x” 100
0.8x 150

Question says,
120 * x = 150 * 0.8x
Yes it is, 150 * 0.8 = 120.
Answer choice “C” matches the condition that, 120 times the initial cost is equal to the total cost.
So the answer is C.
Hope this helps

Plug in some values it will be a matter of 30 seconds -

Now, multiple quantity by 10 Amount changes as well and we have the complete calculation in line of the problem -

Answer is definitely (C)

We can let q = the normal quantity purchased and p = the regular price. Thus:

(1.5q)(0.8p) = 120p

(1.5q)(0.8) = 120

1.2q = 120

q = 120/1.2 = 100

Answer: C

Hi All,

This prompt can also be solved with a combination of TESTing VALUES.

Here's how we can TEST VALUES using 'round numbers':

Regular price = $10 each
Discount price = $8 each

To get the discounted price, we have to buy 50% more calendars... and that total spent would be 120 times $10...

(1.5X)($8) = (120)($10)
$12X = $1200
X = 100 calendars

Final Answer:

GMAT assassins aren't born, they're made,
Rich

If a stationery store owner buys 20% more identically-priced calendars than she usually purchases, she will be given a 20% discount off the standard price. Her total cost would then be 120 times the dollar value of the standard price of one calendar. How many calendars does she usually purchase?

Let's say she buys A calendars for $B per calendar. She pays a total of $AB for A calendars.

Now if she buys 50% more calendars = 3A/2, she pays 20% less price per calendar = $4B/5. She pays a total of $3A/2 * 4B/5 = $6AB/5

The question says that the new amount ($6AB/5) = 120 times the price of each calendar = $120B

6AB/5 = 120B will give me value of A. A = 100.

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