Join ExamsbookAnswer : 2. "21 months"
A man saves Rs. 200 in each of the first three months of his service. In each of the subsequent months his saving increases by Rs. 40 more than the saving of immediately previous month. His total saving from the start of service will be Rs. 11040 after ?5
Q: A man saves Rs. 200 in each of the first three months of his service. In each of the subsequent months his saving increases by Rs. 40 more than the saving of immediately previous month. His total saving from the start of service will be Rs. 11040 after ?
- 119 monthsfalse
- 221 monthstrue
- 318 monthsfalse
- 420 monthsfalse
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Answer : 2. "21 months"
Explanation :
Answer: B) 21 months Explanation: Total savings = 200 + 200 + 200 + 240 + 280 + ... to n months = 11040 = 120 + 80 + 160 + 40 + 200 + 240 + ....n terms= 40 + 80 + 120 + 160 + 200 + 240 + ...n terms= n/2[2a + (n-1)d] + 80 + 40 = 11040= n/2[240 + (n-1)40] = 10920= n[6+n-1] = 546= n[n+5] = 546n = 21