The sum of the series below is 10,900. how many numbers, n, are in the series ? 27 100 109 135

109

Step-by-step explanation:

Given arithmetic progression 19 + 20.5 + 22 + 23.5 + ... + 181

Here the first terma_1=19

The last term=a_n=181

The common differenced=a_2-a_1=20.5-19=1.5

We know that for n terms , the last term a_n=a_1+(n+1)d

19+(n-1)1.5=181\\\Rightarrow(n-1)1.5=181-19\\\Rightarrrow(n-1)1.5=162\\\Rightarrow(n-1)=\frac{162}{1.5}\\\Rightarrow\ n-1=108\\\Rightarrow\ n=108+1\\\Rightarrow\ n=109

but which class are u may know that first

the answer is 11.2 (i know i’m late)