model 5 income & expenditure Section-Wise Topic Notes With Detailed Explanation And Example Questions

Answer: (b)

Let the required income be Rs.x Average monthly income

= Rs.$(80800/16)$ = Rs.5050

x = 120% of 5050

= Rs.$(120/100 × 5050)$ = Rs.6060

Answer: (a)

Let man's income = Rs.100

Savings = 100 – 75 = Rs.25

New income = Rs.120

Savings = $120 - {75 × 115}/100 = 120 - 345/4$

= ${480 – 345}/4 = Rs.135/4$

Increase in savings =$135/4 - 25 = Rs.35/4$

Percentage increase = ${35/4}/25 × 100 = 35%$

Answer: (b)

Savings = 100% - 66$2/3$%

= 33$1/3$% Since, 33$1/3$% ≡ Rs.1200

100% ≡ $1200/100 ×3 × 100$ = Rs.3600

Expenses = 3600 - 1200 = Rs.2400

Aliter : Using Rule 20,

{If a person saves ‘R' rupees after spending x% on food, y% on cloth and z% on entertainment of his income then,

Monthly income = $100/{100 - (x + y +z)}× R$}

Here, R = Rs.1200; x = 66$2/3$%

Monthly income = $100/{100 - 66{2}/3} × 1200$

= $100/{100 - 200/3} × 1200$

= $300/100 × 1200$ = Rs.3600

Expenses = Income – savings = 3600 – 1200 = 2400

Answer: (b)

Radha's total percentage expenditure

= (40 + 20 + 10 + 10)% = 80%

Percentage savings =100 – 80 = 20%

Now, 20% of her total salary = 1500

Her total salary = ${1500 ×100}/20$ = Rs.7500

Using Rule 20,

Here, Monthly income = $100/{100 - (40 + 20 +10 +10)} ×1500$

= $150000/{100 – 80} = 150000/20$ =Rs.7500

Answer: (b)

Simple method

Required answer = $(20/{100 + 20} × 100)$%

= $(20/120 × 100)% = 50/3% = 16{2}/3%$

Answer: (a)

Effective change

= $(–25 + 25 - {25 × 25}/100)%$ = – 6.25%

The negative sign shows decrease.

Percentage decrease = $a^2/100 % = (25)^2/100$

= $625/100$ = 6.25%