UPSC CAPF Assistant Commandant Model Paper 7

Given,
Annual income of Ravi = Rs. x
Formula:
If x% increase any value, then increase value = Actual value × [(100 + x)/100]
Calculation:
Let Ravi’s annual income be Rs. 100 (taking x = 100)
Ravi’s annual expenditure = 100 × [80/100] = Rs. 80
His annual savings = 100 – 80 = Rs. 20
His new annual income = 100 × [125/100] = Rs. 125
His new annual expenditure = 80 × [120/100] = Rs. 96
His new annual savings = 125 – 96 = Rs. 29
His annual savings increased by = 29 – 20 = 9
∴ His annual savings increased by (in %) = [9/20] × 100 = 45%