4. Five marks example problems II

1. Find the sum of \(0.40 + 0.43 + 0.46 + … + 1\).

 

Answer:

 

Sum \(=\)

 

 

2. How many terms of the series \(1 + 5 + 9 + …\) must be taken so that their sum is \(190\)?

 

 

 

3. The \(13^{th}\) term of an A.P. is \(3\) and the sum of first \(13\) terms is \(234\). Find the common difference and the sum of the first \(21\) terms.

 

Common difference \(=\) $\frac{i}{i}$

 

The sum of first \(21\) terms \(=\)