In just over a month I’ll be taking the GMAT as part of my application for grad school. I’ve always had roughly the same scores on the math and verbal sections of standardized tests, so I thought my preparation would consist mostly of familiarizing myself with the test format, etc.

The diagnostic test I took the other night, however, “diagnosed” that I’ve forgotten nearly everything I learned in highschool freshman geometry in 1995. I’ve also seemingly forgotten how to “do math” altogether…

Can you answer the following? (See the answers below)***

Question 1

A train traveling at 100 kmph overtakes a motorbike traveling at 64 kmph in 40 seconds. What is the length of the train in meters?

A. 1777 meters
B. 1822 meters
C. 400 meters
D. 1111 meters
E. None of these

Question 2

How many zeros will be there in the value of 25!?

A. 25
B. 8
C. 6
D. 5
E. 2

Question 3

What is the sum of all 3 digit numbers that leave a remainder of ‘2′ when divided by 3?

A. 897
B. 164,850
C. 164,749
D. 149,700
E. 156,720

Please just shoot me.

The GMAT is a computer-administered test that tries to “peg” you by providing you with harder or easier questions based on the correctness of your previous responses. There is no going back to correct answers, no skipping of questions to return later, and an average of two minutes budgeted for each question, so you can’t take too long on any one particular question or you won’t finish the test. Oh, and did I mention that they don’t allow any calculators?

When you shoot me, please be sure to shoot me dead.

I sense some serious stockinette knitting coming on. Maybe I’ll start a throw blanket consisting of entirely garter stitch. …..knit, knit, knit knit, turn, knit, knit knit knit…

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***If you for some sick and inexplicable reason want to know the answers to the very important sample questions posed earlier, here are the answers:

Explanatory Answer 1

The correct choice is (C) and the correct answer is 400 meters.

Note: When a train overtakes another object such as a motorbike, whose length is negligible compared to the length of the train, then the distance traveled by the train while overtaking the motorbike is the same as the length of the train.

The length of the train = distance traveled by the train while overtaking the motorbike
= relative speed between the train and the motorbike * time taken

In this case, as both the objects i.e., the train and the motorbike are moving in the same direction, the relative speed between them = difference between their respective speeds = 100 – 64 = 36 kmph.

Distance traveled by the train while overtaking the motorbike = 36 kmph * 40 seconds.

The final answer is given in meters and the speed is given in kmph and the time in seconds.

So let us convert the given speed from kmph to m/sec.

1 kmph = 5/18 m/sec

Therefore, 36 kmph = 36 * 5 /18 = 10 m/sec.

Relative speed = 10 m/sec. Time taken = 40 seconds.

Therefore, distance traveled = 10 * 40 = 400 meters.

Explanatory Answer 2

The correct choice is (C) and the correct answer is 6.

25! is factorial 25 whose value = 25*24*23*22*…..*1

When a number that has 5 as its factor is multiplied by another number that has 2 as its factor, the result will have ‘0’ in its units digit. (product of 5 and 2 is 10 and any number when multiplied with 10 or a power of 10 will have one or as many zeroes as the power of 10 with which it has been multiplied)

In 25!, the numbers that have 5 as their factor are 5, 10, 15, 20, and 25. 25 is the square of 5 and hence has two 5’s in it.

Therefore, 25! contains in it 6 fives.
There are more than 6 even numbers in 25!. Hence, the limiting factor is the number of 5s.

And hence, the number 25! will have 6 zeroes in it.

Explanatory Answer 3

The correct choice is (B) and the correct answer is 164,850.

The smallest 3 digit number that will leave a remainder of 2 when divided by 3 is 101.

The next number that will leave a remainder of 2 when divided by 3 is 104, 107, ….

The largest 3 digit number that will leave a remainder of 2 when divided by 3 is 998.

So, the given series is an AP with the first term being 101 and the last term being 998 and thhe common difference being 3.

Sum of an AP = [(First Term + Last Term) / 2] * Number of Terms
]

We know that in an A.P., the nth term an = a1 + (n – 1)*d

In this case, therefore, 998 = 101 + (n – 1)* 3

i.e., 897 = (n – 1) * 3

Therefore, n – 1 = 299

Or n = 300.

Sum of the AP will therefore, be [(101+998)/2] * 300 = 164,850