What is the cost to fence a rectangular plot at the rate of $20/meter?...
Steps 1 and 2 – Understand the question and draw inferences
To find – Cost to fence a rectangular plot at $20/meter
Given –
- Rectangular plot
- Rate of fencing -$20/meter
Approach –
- Fencing a rectangular plot implies going around its perimeter.
- So we need to find the perimeter of the rectangular plot.
- For this we need the value of the sum of the length and the width.
Step 3 – Analyze Statement (1)
Statement (1): If length of the plot is increased by 10 meters, the area of the plot increases by 100 sq. m.
Let’s assume the length and the width of the plot as ‘a’ and ‘b’ meters.
New Length = a + 10
New Area = (a+10) * b
Original Area = a * b
According to Statement (1):
(a + 10) * b = a * b + 100
Simplifying this further we get:
- ab + 10b = ab + 100
- 10b = 100
- b = 10
Even though we know the value of b, we cannot find the value of a since no other information is provided about the rectangular plot.
Thus, this statement does not provide any information about the sum of the length and the width and hence the information is not sufficient to arrive at a unique answer.
Step 4 – Analyze Statement (2)
Statement II: If length of the plot is increased by 10% and width of the plot is decreased by 10%, the perimeter decreases by 5%.
Let’s assume the length and width of the plot as ‘a’ and ‘b’ meters.
Original perimeter = 2(a + b)
New Length = a + 0.1a = 1.1a
New Width = b -0.1b = 0.9b
New perimeter = 2(1.1a + 0.9b)
According to Statement (2):
2(1.1a + 0.9b) = 0.95 (2(a + b))
- 1.1a + 0.9b = 0.95a + 0.95b
- 0.15a = 0.05b
- 3a = b
Even though we know the relationship between a and b, we cannot find the value of sum of a and b since no other information is provided.
Thus, this statement does not provide any information about the sum of length and width and hence the information is not sufficient to arrive at a unique answer.
Step 5 – Analyze both Statements Together
- Per Statement (1): b = 10
- Per Statement (2): 3a = b
So combining these two statements, we can find individual values of a and b and hence we can find the sum of a and b.
Thus implies that we can find a unique answer to the question about determining the cost of fencing at the given rate.
Thus, Statements (1) and (2) together yield a unique answer.
Correct Answer Choice – Choice C