linear equations mcq pdf Model Questions & Answers, Practice Test for ibps rrb so officer sclae 2 3 single exam 2024

Answer: (a)

Let the ten's digit be x.

Then, number = 10x + 3 and sum of digits = (x + 3).

So, (x + 3) = $1/7$ (10x + 3)

⇔ 7x + 21 = 10x + 3 ⇔ 3x = 18 ⇔ x = 6.

Hence, the number is 63.

Answer: (d)

Suppose husband's age be H years.

Then wife's age W = H - 9

Son's age S = ${H - 9}/2$

Daughter's age D = $H/3$

According to question,

$H/3 + 7 = {H - 9}/2$

⇒ 2H + 42 = 3H - 27

⇒ H = 42 + 27 = 69

∴ W = 60.

Solving through option (c).

45+9 = 54 H.

D = 18, S = 22.5 → Difference is 4.5 years, so this is incorrect

Solving through option (d) matches all conditions.

Answer: (d)

(x - 3) (2x + 1) = 0

⇒ (x - 3) = 0 or (2x + 1) = 0

when x - 3 = 0, x = 3

when 2x + 1 = 0 ⇒ x = - $1/2$

When x = 3, then (2x + 1) = 7 and when x = - $1/2$,

then 2x + 1 = 0,

Possible values of (2x + 1) are 0 and 7.

Answer: (b)

Given 4x - y = 2 or 4x - y - 2 = 0

and 2y - 8x + 4 = 0 or - 8x + 2y + 4 = 0

Therefore $a_1 = 4; b_1 = - 1; c_1 = - 2$

$a_2 = -8; b_2 = 2; c_2 = 4$

Now, $a_1/a_2 = b_1/b_2 = c_1/c_2$

⇒ $4/{- 8} = {- 1}/2 = {-2}/4$

This is true only when system of equations has infinitely many solutions.

Answer: (c)

Let the numbers be x, x + 2 and x + 4

Then, x + (x + 2) + (x + 4) = x + 20

⇔ 2x = 14 ⇔ x = 7.

∴ Middle number = x + 2 = 9.