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

Answer: (a)

10% of A = 15% of B = 20% of C

10A = 15B = 20C

${10A}/60 = {15B}/60 = {20C}/60$

$A/6 = B/4 = C/3$

A : B : C = 6 : 4 : 3

6x + 4x + 3x = 7800

13 x = 7800

x = $7800/13$ = 600

B's income = 4x = 600 × 4 = Rs.2400

Answer: (b)

Suppose monthly income of the man is Rs. x.

Expenditure on food = 40% of x = Rs.${2x}/5$

Remaining amount = x - ${2x}/5= Rs.{3x}/5$

Expenditure on transport = $1/3 × {3x}/5 = Rs.x/5$

Remaining amount = ${3x}/5 - x/5 = {2x}/5$

According to question $1/2 × {2x}/5 = 4500$

x = 4500 × 5 = Rs.22,500

Answer: (a)

Using Rule 9,

Shortcut method

Required percentage = $25/{100 - 25}×100$

= $100/3 = 33{1}/3%$

Answer: (d)

Let income be Rs.100

Sum given to elder son = 20% of Rs.100 = Rs.20

Remaining Sum = Rs. 80

Sum given to younger son = 30% of Rs.80 = Rs.24

Remaining sum = Rs.(80 – 24) = Rs. 56

Sum given to the trust = 10% of Rs.56 = Rs.5.6

Remaining sum = Rs.(56 – 5.6) = Rs.50.4

When Rs.50.4 remains, total income = Rs.100

When Rs.10080 remains, total income = ${100 × 10080}/50.4$ = Rs.20000

Here, R = Rs.10080; x = 20%, y = 30%, and z = 10%

Monthly income = $100/{100 – (20 +24 + 5.6)} ×10080$

= $1008000/{100 – 49.6} = 1008000/50.4 = 20,000$

Answer: (b)

Let B's salary = Rs.100

C's salary = Rs.400

and A's salary = Rs.40

Required percentage = $40/400 ×100$ = 10%

Answer: (c)

Using Rule 8,

Simple method

x = $(10/{100 + 10} × 100)$%

= $(1000/110)% = (100/11)% = 9{1}/11%$

Note : If A is r% more than B, then B is

$(r/{100 + r} × 100)$% less than A