Source: Economist GMAT
In a sequence of 40 numbers, each term, except for the first one, is 7 less than the previous term. If the greatest term in the sequence is 281, what is the smallest term in the sequence?
A. 8
B. 7
C. 1
D. 0
E. −6
The OA is A
In a sequence of 40 numbers, each term, except for the first
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Say the first term = a; thus, the 2nd term = a - 7; the 3rd term = a - 7 - 7 = a - 2*7; the 4th term = a - 3*7;BTGmoderatorLU wrote:Source: Economist GMAT
In a sequence of 40 numbers, each term, except for the first one, is 7 less than the previous term. If the greatest term in the sequence is 281, what is the smallest term in the sequence?
A. 8
B. 7
C. 1
D. 0
E. −6
The OA is A
Thus, the 40th term = a - 39*7
Since terms are decreasing in value, the smallest term would be the 40th term and the greatest term would be the first term = a = 281.
Thus, the smallest term = a - 39*7 = 281 - 273 = 8
The correct answer: A
Hope this helps!
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Since each term, except for the first one, is 7 less than the previous term, it must mean the first term is the greatest term, i.e., a_1 = 281. The smallest term must be the last term, i.e., the 40th term.BTGmoderatorLU wrote:Source: Economist GMAT
In a sequence of 40 numbers, each term, except for the first one, is 7 less than the previous term. If the greatest term in the sequence is 281, what is the smallest term in the sequence?
A. 8
B. 7
C. 1
D. 0
E. −6
The OA is A
The sequence depicted is also an arithmetic sequence, and we know that the nth term of an arithmetic sequence has the formula a_n = a_1 + d(n - 1). The variable d is the common difference, and here the common difference is -7 (since each term is 7 less than the previous term). Thus, we have
a_40 = 281 + (-7)(40 - 1)
a_40 = 281 - 7(39)
a_40 = 281 - 273
a_40 = 8
Answer: A
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