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BBA-DBE Bangalore 2025 PYQsQuantitative Ability. Free, no login required.

Find the area (in square units) bounded by x=6,y=0,3x−2y=0x=6, y=0, 3x-2y=0, and x−4y+10=0x-4y+10=0.

Solution

✅ Correct Option: 4

We need to find the area enclosed by four boundary lines.

Let's rewrite each line in slope-intercept form:

x=6x = 6 is a vertical line

y=0y = 0 is the x-axis

3x−2y=03x - 2y = 0 gives us y=3x2y = \dfrac{3x}{2}

x−4y+10=0x - 4y + 10 = 0 gives us y=x+104y = \dfrac{x + 10}{4}


Find where each pair of lines intersects:

Intersection of y=0y = 0 and y=3x2y = \dfrac{3x}{2}:

Setting equal: 0=3x20 = \dfrac{3x}{2} gives us x=0x = 0

Point: (0,0)(0, 0)

Intersection of y=0y = 0 and x=6x = 6:

Point: (6,0)(6, 0)

Intersection of x=6x = 6 and y=x+104y = \dfrac{x + 10}{4}:

Substituting: y=6+104=164=4y = \dfrac{6 + 10}{4} = \dfrac{16}{4} = 4

Point: (6,4)(6, 4)

Intersection of y=3x2y = \dfrac{3x}{2} and y=x+104y = \dfrac{x + 10}{4}:

Setting equal: 3x2=x+104\dfrac{3x}{2} = \dfrac{x + 10}{4}

Cross multiply: 12x=2x+2012x = 2x + 20

Solving: 10x=2010x = 20, so x=2x = 2

Then y=3(2)2=3y = \dfrac{3(2)}{2} = 3

Point: (2,3)(2, 3)


Split the quadrilateral into two triangles:

Triangle 1: (0,0)(0,0), (2,3)(2,3), (6,0)(6,0)

Triangle 2: (2,3)(2,3), (6,4)(6,4), (6,0)(6,0)

Using the triangle area formula:

Area = 12∣x1(y2−y3)+x2(y3−y1)+x3(y1−y2)∣\dfrac{1}{2}|x_1(y_2-y_3) + x_2(y_3-y_1) + x_3(y_1-y_2)|

Triangle 1 area:

12∣0(3−0)+2(0−0)+6(0−3)∣=12∣0+0−18∣=9\dfrac{1}{2}|0(3-0) + 2(0-0) + 6(0-3)| = \dfrac{1}{2}|0 + 0 - 18| = 9

Triangle 2 area:

12∣2(4−0)+6(0−3)+6(3−4)∣=12∣8−18−6∣=12×16=8\dfrac{1}{2}|2(4-0) + 6(0-3) + 6(3-4)| = \dfrac{1}{2}|8 - 18 - 6| = \dfrac{1}{2} \times 16 = 8

Total Area = 9+8=179 + 8 = 17 square units

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