Exercise: 1-F
Multiple Choice Type
Q1: The addition of -30, -15, -10, 20 and 15 is:
Step-by-step:
= (-30) + (-15) + (-10) + 20 + 15
= -30 -15 -10 +20 +15
= (-55) + 35
= -20
Correct Answer: (i) -20
Q2: Two integers a and b are such that a ÷ b = -2; then (a, b) is :
Try each option:
Option (i): (-8 ÷ -4) = 2 ❌
Option (ii): (-2 ÷ 4) = -0.5 ❌
Option (iii): (6 ÷ -3) = -2 ✅
Option (iv): (10 ÷ 5) = 2 ❌
Correct Answer: (iii) (6, -3)
Q3: 15 ÷ (-5) – (2 × -3) is equal to:
Step-by-step:
15 ÷ (-5) = -3
2 × (-3) = -6
Now, plug into expression:
= -3 – (-6)
= -3 + 6
= 3
Correct Answer: (iii) 3
Q4: 7 – 8 ÷ (-2) + 3 × (-4) is equal to:
Step-by-step:
= 7 – (8 ÷ -2) + (3 × -4)
= 7 – (-4) + (-12)
= 7 + 4 – 12
= 11 – 12
= -1
Correct Answer: (iv) -1
Q5: \(-\left[8-\left\{11+30\div\left(4-\overline{7-5}\right)\right\}\right] \) is equal to
Simplify step-by-step:
Inner bracket: (7 – 5) = 2
Then: (4 – 2) = 2
Then: 30 ÷ 2 = 15
Now: 11 + 15 = 26
Then: 8 – 26 = -18
Apply outer negative sign:
= -(-18) = 18
Correct Answer: (ii) 18
Q6: The number that must be subtracted from -2 to get -15 is :
Let the number be x:
-2 – x = -15
⇒ -x = -15 + 2 = -13
⇒ x = 13
Correct Answer: (iv) 13
Q7: \(\left\{-2\div\left(-\frac{1}{2}\right)\right\}\left\{-3\div\left(-\frac{1}{3}\right)\right\}\left\{-4\div\left(-\frac{1}{4}\right)\right\}\) is equal to:
Step-by-step:
-2 ÷ (-½) = 4
-3 ÷ (-⅓) = 9
-4 ÷ (-¼) = 16
⇒ 4 × 9 × 16
Correct Answer: (ii) 4 × 9 × 16
Q8: (-45) × 0 + (-45) ÷ 0 is equal to:
Step-by-step:
(-45) × 0 = 0
(-45) ÷ 0 is undefined ❌
Hence the whole expression is undefined
Correct Answer: (iv) none of these
Q9: 5 ÷ [5 + {5 – (5 – (5 – 5))}]
Solve inner brackets:
(5 – 5) = 0
(5 – 0) = 5
{5 – 5} = 0
Now: 5 + 0 = 5
So expression becomes:
5 ÷ 5 = 1
Correct Answer: (ii) 1
Q10: \(12\div\frac{2}{9}\times2\frac{1}{4}\) is:
Step-by-step:
2¼ = 9/4
12 ÷ (2/9) = 12 × (9/2) = 54
Now: 54 × (9/4) = (54 × 9)/4 = 486/4 = 121.5
Correct Answer: (iv) none of these
Q11: (-3) × [5 + (-9)] is equal to:
Step-by-step:
5 + (-9) = -4
Now: (-3) × (-4) = 12
Correct Answer: (ii) 12
Q12: Liquid at 15°C is cooled to -5°C. The fall in temperature is:
Step-by-step:
Fall = Initial – Final = 15 – (-5) = 15 + 5 = 20°C
Correct Answer: (iii) 20°C
Q13: The number 25 is decreased by 6 every second. What is the total decrease in 6 seconds?
Step-by-step:
Decrease per second = 6
In 6 seconds: 6 × 6 = 36
Correct Answer: (iv) 36
Q14: A = -9, B = -12, C = 10; What is A + B – C?
Step-by-step:
A + B – C = -9 + (-12) – 10 = -21 – 10 = -31
Correct Answer: (ii) -31
