HOT Competition: Set A consists of five integers: 2, 4, 5, 6, and 7. X

Question

Set A consists of five integers: 2, 4, 5, 6, and 7. X is a three digit number formed by using the digits from set A and Y is a two digit number formed by using the remaining digits from set A, such that all the digits are used only once. For example, X = 245 and Y = 67. If X + Y = 501, how many such pairs of integers can be formed?

A. None
B. One
C. Four
D. Six
E. Eight

This question was provided by Crack Verbal
for the Heroes of Timers Competition

A. None 
B. One 
C. Four 
D. Six 
E. Eight

GMATinsight · Accepted Answer

Answer: Option C

Please check the video for the step-by-step solution.

GMATinsight's Solution

https://www.youtube.com/watch?v=bFh4_JqTYCQ

logro · Answer

Given that X is a 3 digit number and Y is a 2 digit number and X+Y=501
Let each digits of X be ABC and Y be DE such that A,B,C,D and E represent the integers from the Set

So for X+Y=501 to hold true we know that C+E should be 1

Now from the given set of integers {2,4,5,6,7}, let's identify the pairs that lead to C+E = 1

The possible combinations of C&E are {4,7} or {5,6}

Now since the Hundred's place of the equation X+Y is 501 and we know that the highest possible value of Y (a 2 digit number) is 76, implying X 425

For the equation to be true, We can safely deduce that no matter what the value of Y is, the hundred's place of X will always be 4

Hence A=4 which translates to 4BC and DE as the numbers

Now since 4 is already used in here the possible combinations of C&E are {5,6}

Which leaves us with the possible values of B&D as {2,7}

So the 1st set could be {425,76},{426,75},{476,25} and {475,26}

mitulsalecha · Answer

Given digits are: {4, 5, 7, 8, 9}.

In order the units digit of the sum to be 5, the units digits of the two integers must be 7 and 8. Thus 2 cases are possible:

AB7
+C8
___
555

OR:

AB8
+C7
___
555

Clearly A must be 4:

4B7
+C8
___
555

OR:

4B8
+C7
___
555

B and C can be 5 and 9 or vise-versa.

Therefore there are total of 4 pairs: (457, 98), (497, 58), (458, 97), and (498, 57).

Answer: D.

NiftyNiffler · Answer

Set A consists of five integers: 2, 4, 5, 6, and 7. X is a three digit number formed by using the digits from set A and Y is a two digit number formed by using the remaining digits from set A, such that all the digits are used only once. For example, X = 245 and Y = 67. If X + Y = 501, how many such pairs of integers can be formed?

A. None
B. One
C. Four
D. Six
E. Eight

This question was provided by Crack Verbal
for the Heroes of Timers Competition

For the sum to be 501, we need 4 in the hundred's place in 4xx and yy format.

Of the remaining digits only 5 & 6 add up to leave 1 in 1's place. That leaves us with 2 & 7 in the 10's place.

So, the possible combinations are (425, 76), (426, 75), (475, 26) & (476, 25).

Hence, the answer is  C

Abhineetegi · Answer

4 pairs can be formed : (425,76) (426,75) ( 475,26) (476,25).. IMO 4

yashikaaggarwal · Answer

If X+Y = 501
Either of X or Y have to an odd number. Other will be even no.
Plus the three digit number will never be 5xx,6xx,7xx because then the number itself will be more than sum.
So the hundred digit will be either 2 or 4
Let X = 4xx,2xx

The unit digit of both x and y have to be either 6 or 5
Because its sum give 1 as unit digit.
7&4 pain can't work as 4 is the hundred digit.

So X = 4x6 or 4x5
Y = y5 or y6

Put X and Y as rest no.(2&7) One by one
1) Let X = 475 and y will be 26 
X+Y = 501
2) Let X = 425 and Y will be 76
X+Y = 501
3) Let X = 426 and Y will be 75
X+Y = 501
4) Let X = 476 and Y will be 25
X+Y = 501

There are 4 such pairs.
Answer must be C

Posted from my mobile device

Varunsawhney8 · Answer

Set A consists of five integers: 2, 4, 5, 6, and 7. X is a three digit number formed by using the digits from set A and Y is a two digit number formed by using the remaining digits from set A, such that all the digits are used only once. For example, X = 245 and Y = 67. If X + Y = 501, how many such pairs of integers can be formed?

A. None
B. One
C. Four
D. Six
E. Eight

This question was provided by Crack Verbal
for the Heroes of Timers Competition

A. None
B. One
C. Four
D. Six
E. Eight

Look For Sum to be 501

Hundredth Digit of X should be 4

Now for unit digit of sum is 1
It means 
Unit digit of X and Y is 4 or 7 and 5 or 6 (Vice versa)

As we cannot use 4 as unit digit 
we will use 5 or 6 as unit digits of X and Y
As we have 1 choice for hundredth digit of X =4
We have 2 possibility for tenth digit of X= 2 or 7
We have 2 possibility for unit digit of X= 5 or 6

We have 2 possibility for tenth digit of Y= 2 or 7
We have 2 possibility for unit digit of Y= 5 or 6

Only 4 Cases are possible
Possibilities are

425+76
426+75
475+26
476+25

ShubhamRastogi · Answer

You can not form any 2 digit no with 4. So options available : 2, 5, 6, 7

Now if you keep in units digit 2 then balance would be 9 and that is not possible
Further any number formed with 6 will need 3 as the difference would be in thirties and this is not possible.
Now same for numbers with 5, difference would be in fourties and 2 4's are not allowed

So numbers remaining : 70's and 20's

76 and 75 are possible
26 and 25 are possible

So 4

Pranavb1302 · Answer

Set = {2,4,5,6,7}
Let us assume
X = abc
Y = ef

Since x+y= 501 (ones place = 1)
i.e. c+f = _1
Therefore c+f = 5+6 = 6+5
-------------------> 2 cases

501 (10th place = 0)

therefore b+e = 1(carry forward from 5+6)+7+2 = 1+2+7
-------------------> 2 cases
and a = 4
--------------------
Therefore total 4 cases are possible.

Posted from my mobile device

raunaqkapoor · Answer

2 units digit combo possible for this are 5,6 and 7,4

now for 5,6 one combination exists: 425+76
for 7,4 there is no combo as 4 has to be in units digit and there is no other combo can add up to 501

hence answer is one

Siak0730 · Answer

this question can be solved using basic counting method.
For X+Y = 501
and X is a 3 digit number
and Y is a 2 digit number
 all the digits are used only once 
Digits can be formed using 2, 4, 5, 6, 7
 Obviously, X cant be 5ab , 6ab, 7ab (all 3 are > 501) or 2ab (as y is just a 2 digit number)
 
 Also, 501 unit digit is 1, the only 2 digit at unit place that after adding up will give 1 is 5 and 6

So, X = 4a5, 4a6
possible cases: 425, 426
 475, 476
 
In that case, when x is above of 4 numbers, Y can be
501-425= 76 (possible)
501-426= 75 (possible)
501-475= 26 (possible)
501-476= 25 (possible)

Total 4 pair of integers are possible.
hence, Answer is C

JonShukhrat · Answer

The numbers we can use are: 2, 4, 5, 6, and 7.
We need to get 501 with the addition of two numbers consisting of above digits.

Let’s start with the three-digit number. It cannot be 2 because the addition of any two-digit number can result in at most  3XY , but not 501.
It cannot be 5, 6, and 7 either because in such case we get a number greater than 501.
So, only  4XY  works.

Next, the sum of the last digits should give  X1 , and the only contenders are 5 and 6. We can write either  4X6  +  Y5  or  4X5  +  Y6 . X and Y can be either 2 or 7. Hence, overall we have 4 cases:

426 + 75; 425 + 76; 475 + 26; 476 + 25

Hence   C

Posted from my mobile device

GKomoku · Answer

Set A consists of five integers: 2, 4, 5, 6, and 7. X is a three digit number formed by using the digits from set A and Y is a two digit number formed by using the remaining digits from set A, such that all the digits are used only once. For example, X = 245 and Y = 67. If X + Y = 501, how many such pairs of integers can be formed?

A. None
B. One
C. Four
D. Six
E. Eight

Given digits are: (2, 4, 5, 6, 7).

In order the units digit of the sum to be 1, the units digits of the two integers must be 5 and 6 OR 7 and 4.
Thus 2 cases are possible for 5 and 6. But we don't take into consideration 7 and 4 possibility, because in this case we cannot get sum 501 anyway.
So:

Consider last digit of X and Y as 6 and % ans vise versa:

AB5
+C6
____
501

AB6
+C5
____
501

A is most probably 4
so:

4B5
+C6
____

1) 475+26=501
2) 425+76=501

4B6
+C5
____
501

1) 476+25=501
2) 426+75=501

(C) is the answer.

MathRevolution · Answer

A {2,4,5,6,7}

Set Y = {24, 25, 26, 27, 42, 45, 46, 47, 52, 54, 56, 57,62,64,65,67, 72, 74, 75, 76}

Set X{ Remaining three digits like 567, 467......}

X + Y = 501.

=> X + 24 = 501 => X = 477 (Not in Set X)

=>  X + 25 = 501 => X = 476

=>  X + 26 = 501 => X = 475

=> X + 27 = 501 => X = 474(Not in Set X)

=> X + 42 = 501 => X = 459 (Not in Set X)

=> X + 45 = 501 => X = 456 (Not in Set X)

=> X + 46 = 501 => X = 455(Not in Set X)

=> X + 47 = 501 => X = 454(Not in Set X)

=> X + 52 = 501 => X = 449(Not in Set X)

=> X + 54 = 501 => X = 447(Not in Set X)

=> X + 56 = 501 => X = 445(Not in Set X)

=> X + 57 = 501 => X = 454(Not in Set X)

=> X + 62 = 501 => X = 439(Not in Set X)

=> X + 64 = 501 => X = 437(Not in Set X)

=> X + 65 = 501 => X = 436(Not in Set X)

=> X + 67 = 501 => X = 434(Not in Set X)

=> X + 72 = 501 => X = 429(Not in Set X)

=> X + 74 = 501 => X = 427(Not in Set X)

=>  X + 75 = 501 => X = 426

=>  X + 76 = 501 => X = 425

Total 4 pairs of integers.

Answer C

Thekingmaker · Answer

The only problem is just stumbling on the first combinatioin initially i thought it was one however upon further inspectino i figured it out as (426, 75 ) , (475, 26), (476, 25) , (476 , 25) it took me around 3 minute to figure out the first the rest simply fell in place

Crytiocanalyst · Answer

5,6,7 cannot be the starting digits since ot will overshoot the sum of 501 
2 cannot be used since then the value of 501 cannot be attained

It can start from 426, 75 a possibility that satisfies 
remaining numbers can be formed by switching the unit digit place and tens place in 2*2 ways

=4 
Therefore IMO C

bumpbot · Answer

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.

HOT Competition: Set A consists of five integers: 2, 4, 5, 6, and 7. X

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Problem Solving (PS) Questions

HOT Competition: Set A consists of five integers: 2, 4, 5, 6, and 7. X

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards