find the sum 1, 4.5, 8, .............155?
a. 3220 b. 3510 c. 3624 d. none of these
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Answer:
The series above is an AP because 4.5 -1 = 8-4.5
common difference d = 4.5 -1 = 3.5
step 1. find number of terms in the AP
tn = a + (n-1) d
155 = 1 + (n-1) * 3.5 ............(1)
solving (1) n =45
step 2 :
Number of terms * Average of first and last term
= 45 * (155+1)/2 = 3510
a. 3220 b. 3510 c. 3624 d. none of these
Post your answer through comment
Answer:
The series above is an AP because 4.5 -1 = 8-4.5
common difference d = 4.5 -1 = 3.5
step 1. find number of terms in the AP
tn = a + (n-1) d
155 = 1 + (n-1) * 3.5 ............(1)
solving (1) n =45
step 2 :
Number of terms * Average of first and last term
= 45 * (155+1)/2 = 3510
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