Shortcut Trick
Ratio of Salaries A : B = 6 : 7
B’s salary after 5.5% increase = 105.5% = ₹1,47,700
B’s original salary (7 units) = (1,47,700 ÷ 105.5) × 100 = ₹1,40,000
If 7 units = ₹1,40,000, then 1 unit = ₹20,000
A’s salary = 6 units = 6 × ₹20,000 = ₹1,20,000
∴ The correct answer is ₹1,20,000.
Alternate Method
Given:
Ratio of salaries A : B = 6 : 7
Percentage increase in B’s salary = 5(1/2)% = 5.5%
New salary of B = ₹1,47,700
Calculations:
⇒ Let the initial salaries of A and B be 6x and 7x respectively.
⇒ B’s new salary = 7x + (5.5 ÷ 100) × 7x = 1,47,700
⇒ 7x × (1 + 0.055) = 1,47,700
⇒ 7x × 1.055 = 1,47,700
⇒ 7.385x = 1,47,700
⇒ x = 1,47,700 ÷ 7.385
⇒ x = 20,000
⇒ Salary of A = 6x = 6 × 20,000 = 1,20,000
∴ The correct answer is ₹1,20,000.
Additional Information
Percentage Increase Formula
New Value = Original Value × (100 + Increase%) ÷ 100. This is used to find the final value after a hike.
Ratio and Proportion
If A : B = m : n, then A = m × k and B = n × k, where k is a common multiplication factor.
Base Change in Percentages
To find the original value from an increased value: Original = [New Value ÷ (100 + r)] × 100.