Calculate s22 for the arithmetic sequence in which a12=2.4 and the common difference is d=3.4

Option A is correct.

Value of

Step-by-step explanation:

Given: and common difference(d) = 3.4

A sequence of numbers is arithmetic i.e,  it increases or decreases by a constant amount each term.

The sum of the nth term of a arithmetic sequence is given by;

, where n is the number of terms, a is the first term and d is the common difference.

We also know the nth tern sequence formula which is given by ;

                            ......[2]

First find a.

it is given that

Put n =12 and d=3.4 in equation [2] we have;

2.4 = a + 37.4

Simplify:

a = - 35

Now, to calculate

we use equation [1];

here, n =2 , a =-35 and d=3.4

Simplify:

Therefore, the sum of sequence of 22nd term i.e,

he earned 78.75 in interest.

step-by-step explanation: