Question

First term of an ap is 5 the last term.Is 45 and sum.Is 400 find the ni.Ofvterms

Answer 1

a=5

l=45

Sn=400

Sn=n/2*(a+l)

400=n/2*(5+45)

800=n*50

800/50=n

16=n

so, there are 16 no. of terms.