model 2 net increase or decrease in % Section-Wise Topic Notes With Detailed Explanation And Example Questions

Answer: (b)

Let the original number of employees be 100 and wages per head be Rs.100.

Total wages = Rs.(100 × 100) = Rs.10000

New number of employees = 125

New wages per head = Rs.75

Total new wages = Rs.(125 × 75) = Rs.9375

Decrease = Rs.(10000 – 9375) = Rs.625

Percentage decrease =$625/10000 × 100$

=$625/100 = 25/4%$

Answer: (b)

Let the original price be Rs.100

New price after 10% decrease = Rs.90

In order to restore the price to its original value, it must be increased by Rs.10

% increase = $10/90 × 100 = 100/9 = 11{1}/9%$

Required % = $10/{100 - 10} × 100%$

= $100/9% = 11{1}/9$%

Answer: (c)

If the original price of article be Rs.x, then

$x × 80/100 × 130/100$ = 416

$x = {416 × 100 × 100}/{80 × 130}$= Rs.400

Using Rule 5,

Let the number be x

The number increases by

$(- 20 + 30 - {20 × 30}/100)$% = 4%

$x + {4x}/100$ = 416

${104x}/100$ = 416 ⇒ x = 400

Answer: (a)

Let the price of the article be Rs.100 and the daily sale be 100 units.

Revenue day = 100 × 100 = Rs.10000

New receipts = 75 × 130 = Rs.9750

Decrease = Rs.(10000 – 9750) = Rs.250

% decrease = $250/10000 × 100 = 2{1}/2%$

Required change = $(a - b - {ab}/100)$

= $(30 - 25 – {30 × 25}/100)%$

= $(5 - 15/2) = –2.5% = 2{1}/2%$ decrease.

Answer: (c)

Let original fraction be $x/y$

According to the question,

${120/100x}/{{95y}/100} = 5/2$

${120x}/{95y} = 5/2$

$x/y = 5/2 × 95/120 = 95/48$

Answer: (d)

Increase in first year = 10%

Decrease in 2nd year = 10%

Effective result = $(10 - 10 - {10 × 10}/100)% = -1%$

Increase in 3rd year = 10%

Effective result = $(10 - 1 - {10 × 1}/100)$%

= (9 – 0.1)% = 8.9% (increase)