Exercise :: Area  General Questions
11.  The difference between the length and breadth of a rectangle is 23 m. If its perimeter is 206 m, then its area is: 

Answer: Option D Explanation: We have: (l  b) = 23 and 2(l + b) = 206 or (l + b) = 103. Solving the two equations, we get: l = 63 and b = 40. Area = (l x b) = (63 x 40) m^{2} = 2520 m^{2}. 
12.  The length of a rectangle is halved, while its breadth is tripled. What is the percentage change in area? 

Answer: Option B Explanation: Let original length = x and original breadth = y. Original area = xy.
New breadth = 3y.

13.  The length of a rectangular plot is 20 metres more than its breadth. If the cost of fencing the plot @ 26.50 per metre is Rs. 5300, what is the length of the plot in metres? 

Answer: Option E Explanation: Let breadth = x metres. Then, length = (x + 20) metres.
2[(x + 20) + x] = 200 2x + 20 = 100 2x = 80 x = 40. Hence, length = x + 20 = 60 m. 
14.  A rectangular field is to be fenced on three sides leaving a side of 20 feet uncovered. If the area of the field is 680 sq. feet, how many feet of fencing will be required? 

Answer: Option D Explanation: We have: l = 20 ft and lb = 680 sq. ft. So, b = 34 ft. Length of fencing = (l + 2b) = (20 + 68) ft = 88 ft. 
15.  A tank is 25 m long, 12 m wide and 6 m deep. The cost of plastering its walls and bottom at 75 paise per sq. m, is: 

Answer: Option C Explanation:
