(A) 605
(B) 608
(C) 613
(D) 616
(E) 621
For a set of practice problems on sequences, as well as the OA & OE of this particular problem, see:
https://magoosh.com/gmat/2014/gmat-prac ... sequences/
Mike
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Let S be the set of all positive integers that, when divided
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Mike@Magoosh
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Let S be the set of all positive integers that, when divided by 8, have a remainder of 5. What is the 76th number in this set?
(A) 605
(B) 608
(C) 613
(D) 616
(E) 621
For a set of practice problems on sequences, as well as the OA & OE of this particular problem, see:
https://magoosh.com/gmat/2014/gmat-prac ... sequences/
Mike
(A) 605
(B) 608
(C) 613
(D) 616
(E) 621
For a set of practice problems on sequences, as well as the OA & OE of this particular problem, see:
https://magoosh.com/gmat/2014/gmat-prac ... sequences/
Mike
Magoosh GMAT Instructor
https://gmat.magoosh.com/
https://gmat.magoosh.com/
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abhasjha
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To get the numbers in set S use .... N= 8A+5 . putting A=0 we get the first number as 5 .putting A = 1 we get the number = 13 ....
first of such number is 5 ...
next number 13 and next number 21 .....
An Arithmetic series then follows . (one way to look at remainder problems is all remainder problems are in a way arithmetic progessions !)
So there are 76 terms in the series with a common difference of 8.
so tn = a+(n-1)d
= 5+ (75)x8
= 5+600
= 605
Answer A
first of such number is 5 ...
next number 13 and next number 21 .....
An Arithmetic series then follows . (one way to look at remainder problems is all remainder problems are in a way arithmetic progessions !)
So there are 76 terms in the series with a common difference of 8.
so tn = a+(n-1)d
= 5+ (75)x8
= 5+600
= 605
Answer A
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Mathsbuddy
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If the first multiple of 8 is 0, then the 75th true multiple of 8 gives:
75 x 8 + 5 has last digit 5
Answer = A
75 x 8 + 5 has last digit 5
Answer = A
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masoom j negi
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S = 8x + 5
So, terms in S are in A.P. with first term = 5 and common difference = 8
76th term = a + (76 - 1)d = 5+ (75)8= 605
So, terms in S are in A.P. with first term = 5 and common difference = 8
76th term = a + (76 - 1)d = 5+ (75)8= 605
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Scott@TargetTestPrep
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The first number in the set is 5, since 5/8 = 0 remainder 5.Mike@Magoosh wrote:Let S be the set of all positive integers that, when divided by 8, have a remainder of 5. What is the 76th number in this set?
(A) 605
(B) 608
(C) 613
(D) 616
(E) 621
The second number in the set is 5 + 1(8).
The third number in the set is 5 + 2(8).
The fourth number in the set is 5 + 3(8).
Continuing the pattern established, we see that the 76th number in the set is 5 + 75(8) = 605.
Answer: A
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