model 3 reducing & exceeding prices Section-Wise Topic Notes With Detailed Explanation And Example Questions

Answer: (c)

Original rate = Rs.x per egg

New rate = Rs.${6x}/5$ per egg

$24/x - {24 × 5}/{6x} = 2$

$24/x - 20/x = 2$

$4/x = 2 ⇒ x = 2$

New rate = Rs.$12/5$ per egg.

Rate per dozen of eggs

= Rs.$(12/5 × 12)$ = Rs.28.80

Using Rule 31,

New price/present price

= ${20 × 24}/{100 × {2/12}}$ = Rs.28.80

Answer: (a)

Percentage decrease = $0.25/1.25 × 100 = 20%$

Answer: (c)

Original price of article = Rs.x per kg.

New price = Rs.${79x}/100$ per kg

$100/{{79x}/100} - 100/x = 3$

$10000/{79x} - 100/x = 3$

${10000 - 7900}/{79x} = 3$

$2100/{79x} = 3$

$700/{79x} = 1$

$79x = 700 ⇒ x = 700/79$

New price

= ${79x}/100 = 79/100 × 700/79$ = Rs.7 per kg

Using Rule 31,

Reduced price per kg. = ${21 × 100}/{100 × 3}$ = Rs.7

Answer: (b)

The original price of 1 egg = Rs.x

Present price = Rs.$3/2x$

$24/x - 24/{{3x}/2} = 4$

$24/x(1 - 2/3) = 4$

$8/x = 4 ⇒ x = 2$

Present price of eggs per dozen

= $12 × 3/2 × 2 = Rs.36$

Using Rule 31,

New price = ${50 × 24}/{100 × {4/12}}$ = Rs.36

Answer: (c)

Required percent

= $\text"Decrease%"/{100 - \text"Decrease%"}$ × 100

= $10/{100 - 10} × 100 = 100/9 = 11{1}/9%$

Answer: (d)

Let original price of sugar be Rs. x per kg.

New price= Rs.$({120x}/100) =Rs.({6x}/5)$per kg.

According to the question,

$50/x - 50/{{6x}/5} = 2$

$50/x - {50 × 5}/{6x} = 2$

$50/x - 125/{3x} = 2$

${150 – 125}/{3x} = 2$

$6x = 25 ⇒ x = Rs.25/6$ kg.

Required quantity of sugar = $50/x$

= $50/{25/6} = {50 × 6}/25 = 12$kg.