Bottle R contains 250 capsules and costs $6.25. Bottle T contains 130

When the numbers are this gross and the answers are orders of magnitude off from each other, we can estimate.

$6.25 = 625 cents. If a bottle of 250 pills costs 625 cents, each pill is between 2 and 3 cents. (as 250*2 = 500 and 250*3 = 750)
$2.99 = 299 cents. If a bottle of 130 pills costs 299 cents, each pill is between 2 and 3 cents. (as 130*2 = 260 and 130*3 = 390)

While we don't know the exact cost of each pill, we know that since both pills are between 2 and 3 cents, the difference between them must be less than 1 cent. E is the only answer small enough to be possible.

This process should take <30 seconds. Practice honing a sense for when the calculation you're doing/setting up is too hard to be realistic for the test and then refuse to do it — the GMAT isn't about busy work, so if the calculations are too painful, you aren't supposed to be doing them! Often the trick is another way of calculating, but in other cases, like this question, the trick is not calculating at all. A peek at the answer choices is often a good clue to whether or not estimation or a similar method will work: in this case, if the answers were closer together in magnitude, we would have had a much harder time estimating accurately.

This question is a great example of how we can save time by applying GMAT-specific strategies.

First, once we finish reading the question, we should scan the answer choices.
Here, we see that the answer choices are VERY spread apart, which means we can be quite AGGRESSIVE with our estimation.

Given: Bottle R contains 250 capsules and costs $6.25
So, the cost per capsule = $6.25/250
Tip: Dividing a small number by a larger number is a pain, and there are plenty of opportunities to make mistakes. To avoid mistakes, we can simplify matters by converting dollars to cents.
We get: cost per capsule = 625¢/250
Since 500/250 = 2 and 750/250 = 3, we know that 625/250 = 2.something
In other words, the bottle R capsules cost 2.something CENTS each.

Given: Bottle T contains 130 capsules and costs $2.99
We get: cost per capsule = 299¢/130
Since 260/130 = 2 and 390/130 = 3, we know that 299/130 = 2.something
In other words, the bottle T capsules cost 2.something CENTS each.

Since 1 bottle R capsule costs 2.something CENTS , and 1 bottle T capsule costs 2.something CENTS , the DIFFERENCE must be less than 1 CENT (aka $0.01) .

Answer: E

Price per capsule for bottle R= 6.25/250=0.025
for bottle T =0.023 per capsule
difference= 0.002

E

is there link for original discussion ?
I am unable to find a quicker way to calculate
6.25/250
and
2.99/130

the calculation itself is taking more than 2 mins

The difference between the cost per capsule for bottle R and the cost per capsule for bottle T is:

6.25/250 - 2.99/130

0.025 - 0.023 = 0.002

Answer: E
_________________

Bottle R contains 250 capsules and costs $6.25. Bottle T contains 130 capsules and costs $2.99. What is the difference between the cost per capsule for bottle R and the cost per capsule for bottle T?

A. $0.25
B. $0.12
C. $0.05
D. $0.03
E. $0.002

ANS- 1st - 6.25/250 =0.025 and 2nd take 2.99 as 3.00 (aprrox. 1 cent wont make much diff.) this is equal to 0.023. Now difference 0.025-0.023 = 0.002.

R 6.25$ --> 250 Capsule
T 2.99$ --> 130 Capsule

2T = 5.98$ -->260 Capsule

6.25-5.98 = 0.27

0.27/250 = CHECK THE ANSWERS, no need to calculate... you need to multiply by 1000 0.27 to obtain 270, so, the answer must have at least two zeroes before any number 0.00XXXX

\(R = \frac{6.25}{25} = 0.25\)

\(T = \frac{2.99}{13} = 0.23\)

So, Difference per unit is \(\frac{(0.25 - 0.23)}{10} = 0.002\) , Answer must be (E)
_________________

The difference between

1. the cost per capsule for bottle R : 6.25 /250
2. the cost per capsule for bottle T is: 2.99 /130

\(\frac{6.25}{250}\) - \(\frac{2.99}{130}\)
= 0.025 - 0.023
= 0.002

Answer: E

6.25/250= (6250*10^-3)/250
=25*10^-3
3/130 = (3000*10^-3)/130
=23*10^-3

Difference= (25-23)10^-3 =0.002

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