Question

Gaurav has Rs. (7² × 10⁴) in his account and his brother has Rs. (2⁷ × 10³) in his account. If the total amount in their accounts is written in standard form as m × 10ⁿ, then the value of m + n is:
1. 7
2. 11.18
3. 12.7
4. 9

Answer 1

Correct Answer - Option 2 : 11.18

Given 

Gaurav has Rs. (72 × 104) in his account and his brother his Rs. (27 × 103) in his account

Calculation

Total amount in their accounts = (72 × 104) + (27 × 103) = 49 × 10⁴ + 128 × 10³

⇒ 490 × 10³ + 128 × 10³ 

⇒ (490 + 128) × 10³ 

⇒ 618 × 10³ = 6.18 × 10⁵

On comparing it with the standard form m × 10ⁿ we get, m = 6.18 and n = 5

So, m + n = 6.18 + 5 = 11.18