model 8 find monthly income Section-Wise Topic Notes With Detailed Explanation And Example Questions

Answer: (b)

X + Y =Rs.(2 × 5050) =Rs.10100

Y + Z =Rs.(2 × 6250) =Rs.12500

z + x =Rs.(2 × 5200) =Rs.10400

Adding all three,

2 (X + Y + Z) =Rs.(10100 + 12500 + 10400)

=Rs.33000

⇒ X + Y + Z = Rs.16500

∴ X = (X + Y + Z) – (Y + Z)

=Rs.(16500 – 12500) =Rs.4000

Answer: (c)

Total workers = x (let)

∴ 7 × 12000 + (x – 7) × 6000 = 8000 x

⇒ 84000 + 6000 x – 42000 = 8000 x

⇒ 8000 x – 6000 x = 42000

⇒ 2000 x = 42000

⇒ x = $42000/2000$ = 21

Answer: (c)

Required average

=Rs. $({16000 ×19+20000}/20)$

=Rs.$({304000+20000}/20)$

=Rs. $(324000/20)$

=Rs.16200

OR

Difference = Rs. (20000 – 16000) = Rs. 4000

∴ Increase in average = $4000/20$ = Rs. 200

∴ Required average

= Rs. (16000 + 200)

= Rs. 16200

Answer: (c)

Let the average monthly income of man be Rs. x.

∴ Man’s annual income = Rs. 12x

∴ Man’s annual expenses

=Rs.$({6x×12}/8)$

=Rs.9x

∴ Savings = 12x – 9x = Rs. 3x

∴ 3x = 6000

⇒ x = $6000/3$ = Rs. 2000

Answer: (c)

Total monthly income of P and Q = 2 × 5050 =Rs.10100

Total monthly income of Q and R = 2 × 6250 =Rs.12500

Total monthly income of P and R = 2 × 5200 =Rs.10400

On adding all three,

Total monthly income of 2(P + Q + R)

=Rs.(10100 + 12500 + 10400)

=Rs.33000

∴ Total monthly income of (P + Q + R) = $33000/2$

=Rs.16500

∴ P’s monthly income

=Rs.(16500 – 12500)

=Rs.4000