Question

A sum of R.s.3900 is paid off in 12 instalments,such that each instalment is R.s. 10 more than the preceding one. Find the amount of the first and last instalment

Answer 1

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Answer 2

Step-by-step explanation:

S12=3900

d =10

a =?

n =?

S12=12/2× {2a+(12-1)×10}

3900 =6×{2a+11×10}

3900 = 6×{2a+110}

3900/6 =2a+110

650-110=2a

540= 2a

540÷2=a

:.270 =a

S12 = 12/2 (270+ n)

:. n= 380.