Aptitude Algebraic Expressions Test Paper 3

Answer: C

Explanation:

Let the numbers of students be x
Then
12= 128
x-24= 256
x-24-256 = 0
Let =y

Then,

y² - 24y-256=0

y² - (32-8)y-256=0

y(y-32)+8(y-32)=0

(y+8)(y-32)=0

y = - 8,y=32

∴ x=y²= 32²=1024

Answer: A

Explanation:

Let the price of mixer is Rs. x

And, the price of a T.V = Rs y.

As per the question:

2x + y = 7,000........(i)

x + 2y = 9,800 ........(ii)

x = 9800 - 2y

2(9800 - 2y) + y = 7000

19600 - 4y + y = 7000

19600 - 3y = 7000

19600 - 7000 = 3y

12600 = 3y

y= 12600/3 = 4200

Putting the value of y in equation (ii)

x + 2 * 4200 = 9800

x = 9800 - 8400

x = 1400

Answer: B

Explanation:

= 2,

=> = 2

=> 5x + 4y = 8

Also,

= 2

=> = 2

4x + 3y = -5

Solving these equations, we get

x = 4, y = - 3

Answer: C

Explanation:

Let the cost of potatoes per kg = Rs. X

And the cost of tomatoes per kg = Rs. Y

3x + 2y = 32 ........ (i)

x + 4y = 39 ........ (ii)

Solving equation 1 and 2, we get
x = 5,y =

Answer: C

Explanation:

Let the age of Madan and his father be x and y years respectively. Then

y-x = 20 .........(i)

Ten year ago:
x-10= (y-10)

2(x-10) = y - 10

2x - 20 = y - 10

2x - y = - 10 + 20

2x - y = 10

Now solving eq.1 and eq.2:

y - x = 20

- y + 2x = 10

x = 30 (age of Madan)

So, age of his father: y = x + 20

                        = 30 + 20 = 50

Madan's father age after 10 years:

y+10 = 50 + 10 = 60 years