The first Last term of an arithmetic progression are 7 and 43 respectively. The sum of the terms of the progression is 250 Find the number of terms and common difference of the progression
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Given:
- First term (a) = 7
- Last term (L) = 43
- Sum of the terms (Sₙ) = 250
Find the number of terms (n).
The formula for the sum of an arithmetic progression when the first and last terms are known is:
Sₙ = (n/2)(a + L)Substitute the given values into the formula:
250 = (n/2)(7 + 43)
250 = (n/2)(50)
Multiply both sides by 2:
500 = n × 50
Divide by 50 to find n:
n = 500 / 50
n = 10Find the common difference (d).
The formula for the last term of an arithmetic progression is:
L = a + (n - 1)dSubstitute the known values (a, L, and the n we just found) into the formula:
43 = 7 + (10 - 1)d
43 = 7 + (9)d
Subtract 7 from both sides:
43 - 7 = 9d
36 = 9d
Divide by 9 to find d:
d = 36 / 9
d = 4The number of terms is 10 and the common difference is 4.
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