Question

some one please help me with this equation.......... please explain the last equation (with the wierd sign) in the attachment below...

Answer 1

It's not just some weird sign

It's THE weird sign xD

That is known as the sign for summation. It means the sum of the all values of ai upto a"n"

It means all the values of i will be put in the a(i) section upto a(n) and then will get added. Below the summation sign in the i we put the value from which we have to start the sum and above the summation sign we put the value upto which we have to add.

For example,

here let, i=0 and n = 5

then,

{refer to the picture above}

this means

a(mean) = a1+a2+a3+a4+a5/5

and thus we will obtain the sum followed by their Arithmetic mean.

Cheers!