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Progression - Quant/Math - CAT 2009
Question 4 the day:
June 11, 2003
The question for the day is from the topic of Progression.
- The sum of the first 50 terms common to the series 15,19,23 ... and 14,19,24 ... is
| (1) |
25450 |
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(2) |
24550 |
| (3) |
50900 |
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(4) |
Cannot be determined |
Correct Answer - (1)
Solution:
The two series follows A.P. Therefore, the common series should also follows A.P
Common difference of 1st series = 4, Common difference of 2nd series = 5.
Common difference of the identical sequence is given by L.C.M of 4 and 5 = 20
Here the first term of the identical sequence is 19.
We know the sum of first n terms is given by = n/2 [2a + (n –1) d]
Hence the sum of first 50 terms of this sequence = 50/2[2(19) + 49 * 20] = 25450.
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