Question

(ii) How many terms of the A.P. 16, 14, 12, ... are needed to give the sum 60? Explain
why do we get two answers.
(iii) The cost of living index and the number of weeks are given in the following table.​

Answer 1

Answer:

We know that Sn = n/2(2a+(n-1)d)

We know that Sn = n/2(2a+(n-1)d)60 = n/2(2*16+(n-1)(-2))

We know that Sn = n/2(2a+(n-1)d)60 = n/2(2*16+(n-1)(-2))120 = n(34 - 2n)

We know that Sn = n/2(2a+(n-1)d)60 = n/2(2*16+(n-1)(-2))120 = n(34 - 2n)120 = 34n-2n^2

We know that Sn = n/2(2a+(n-1)d)60 = n/2(2*16+(n-1)(-2))120 = n(34 - 2n)120 = 34n-2n^2n^2 -17n+60=0

We know that Sn = n/2(2a+(n-1)d)60 = n/2(2*16+(n-1)(-2))120 = n(34 - 2n)120 = 34n-2n^2n^2 -17n+60=0n^2 -12n-5n+60=0

We know that Sn = n/2(2a+(n-1)d)60 = n/2(2*16+(n-1)(-2))120 = n(34 - 2n)120 = 34n-2n^2n^2 -17n+60=0n^2 -12n-5n+60=0n=5 or 12.

Step-by-step explanation:

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