A carpenter was hired to build 192 window frames. The first day he made five frames and each day, thereafter he made two more frames then he made the day before. How many days did it take him to finish the job ?
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Hi,
Here is your answer,
Here, a = 5 and d = 2
Let the carpenter finished the job in n days.
Then, according to the question, Sn = 192
We know, Sn = n/2 [ 2a + (n -1)d]
→ 192 = n/2 [ 10 + 2n -2]
→ 192 = n/2[ 8 + 2n]
→ 192 = 4n + n²
→ n² + 4n - 192 = 0
→ ( n -12) ( n + 16) = 0
→ n = 12, -16 [ ∴ n ≠ -16]
∴ n = 12
Henc, the carpenter will finish the job in 12 days.
Hope it helps you !
Here is your answer,
Here, a = 5 and d = 2
Let the carpenter finished the job in n days.
Then, according to the question, Sn = 192
We know, Sn = n/2 [ 2a + (n -1)d]
→ 192 = n/2 [ 10 + 2n -2]
→ 192 = n/2[ 8 + 2n]
→ 192 = 4n + n²
→ n² + 4n - 192 = 0
→ ( n -12) ( n + 16) = 0
→ n = 12, -16 [ ∴ n ≠ -16]
∴ n = 12
Henc, the carpenter will finish the job in 12 days.
Hope it helps you !
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