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

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: (a)

Let A's income = Rs.a

and B's income = Rs.b

a × 60% = b × 75%

a × 4 = 5 × b

$b/a = 4/5$

Now, b = a × x%

$b/a = x/100 ⇒ x/100 = 4/5$

$x = 4/5×$ 100 = 80

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: (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

Answer: (a)

Suppose monthly income = Rs.x

Then, $8/3$% of x = 72

x × $8/300$ = 72

${72× 300}/8$ = Rs.2700

Answer: (b)

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

$25/125 × 100$ = 20%