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- Question
If the radius of a circle is decreased by 50% , find the percentage decrease in its area.
Options- A. 75%
- B. 65%
- C. 35%
- D. 25%
- Correct Answer
- 75%
Explanationlet original radius = r and new radius = (50/100) r = r/2
original area = and new area =
decrease in area = * *100 = 75% - 1. If the diagonal of a rectangle is 17cm long and its perimeter is 46 cm. Find the area of the rectangle.
Options- A. 110
- B. 120
- C. 130
- D. 140 Discuss
- 2. If each side of a square is increased by 25%, find the percentage change in its area.
Options- A. 56.25%
- B. 36.25%
- C. 16.25%
- D. 12.25% Discuss
- 3. A mixture is composed of 11 parts of pure milk and 2 parts of water. If 35 litres of water were added to the mixture then the new mixture will contain twice as much pure milk as water, then how many litres of pure milk does the original mixture contain?
Options- A. 110
- B. 55
- C. 220
- D. 70 Discuss
- 4. A beaker contains acid and water in the ratio 1 : x. When 300 ml of the mixture and 50 ml of water are mixed, the ratio of acid and water becomes 2 : 5. What is the value of x?
Options- A. 2
- B. 1
- C. 3
- D. 4 Discuss
- 5. An alloy is made by mixing metal A costing Rs 2000/kg and metal B costing Rs 400/kg in the ratio A:B = 3:1. What is the cost (in Rs) of 8 kilograms of this alloy?
Options- A. 1600
- B. 9800
- C. 6400
- D. 12800 Discuss
- 6. The diagonal of a rectangle is 41 cm and its area is 20 sq. cm. The perimeter of the rectangle must be:
Options- A. 18
- B. 28
- C. 38
- D. 48 Discuss
- 7. A parallelogram has sides 30m and 14m and one of its diagonals is 40m long. Then its area is
Options- A. 136
- B. 236
- C. 336
- D. 436 Discuss
- 8. The percentage increase in the area of a rectangle, if each of its sides is increased by 20%
Options- A. 22%
- B. 33%
- C. 44%
- D. 55% Discuss
- 9. A man walked diagonally across a square plot. Approximately what was the percent saved by not walking along the edges?
Options- A. 10%
- B. 20%
- C. 30%
- D. 40% Discuss
- 10. A wire can be bent in the form of a circle of radius 56cm. If it is bent in the form of a square, then its area will be
Options- A. 7744
- B. 8844
- C. 5544
- D. 4444 Discuss
Area problems
Search Results
Correct Answer: 120
Explanation:
let length = x and breadth = y then
2(x+y) = 46 => x+y = 23
x²+y² = 17² = 289
now (x+y)² = 23²
=> x²+y²+2xy= 529
=> 289+ 2xy = 529
=> xy = 120
area = xy = 120 sq.cm
Correct Answer: 56.25%
Explanation:
Let each side of the square be a. Then, area = .
New side =
. New area =
=
Increase in area =
Increase% =
% = 56.25%.
Correct Answer: 110
Correct Answer: 2
Correct Answer: 12800
Correct Answer: 18
Explanation:
(or)
Also,
= 41 + 40 = 81
(l + b) = 9.
Perimeter = 2(l + b) = 18 cm.
Correct Answer: 336
Explanation:
let ABCD be the given parallelogram
area of parallelogram ABCD = 2 x (area of triangle ABC)
now a = 30m, b = 14m and c = 40m
s=1/2 x (30+14+40) = 42
Area of triangle ABC =
= = 168sq m
area of parallelogram ABCD = 2 x 168 = 336 sq m
Correct Answer: 44%
Explanation:
Let original length = x metres and original breadth = y metres.
Original area = xy sq.m
Increased length = and Increased breadth =
New area =
The difference between the Original area and New area is:
Increase % = = 44%
Correct Answer: 30%
Explanation:
let the side of the square be x meters
length of two sides = 2x meters
diagonal =
= 1.414x m
saving on 2x meters = .59x m
saving % = %
= 30% (approx)
Correct Answer: 7744
Explanation:
length of wire =
= 2 x (22/7 ) x 56 = 352 cm
side of the square = 352/4 = 88cm
area of the square = 88 x 88 = 7744sq cm
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