Expressions using Letter-Numbers — Quiz

Q1. Why are letter-numbers introduced instead of just using words like 'Aftab's age'?

• A. To write mathematical relations in a short, general form
• B. Because words are not allowed in mathematics
• C. To make the chapter look more difficult
• D. Because Hindi and English use different words

Q2. We can use 'a' for Aftab's age. If a teacher in Rampur uses 'x' instead, the expression for Shabnam's age becomes

• A. x = a + 3
• B. x + 3
• C. x - 3
• D. 3x

Q3. Ketaki sells coconut-jaggery laddus. A coconut costs Rs 35 and 1 kg jaggery costs Rs 60. If 'c' is the number of coconuts and 'j' is the kg of jaggery, the total cost expression is

• A. c + j + 95
• B. 35 + 60 × cj
• C. c × 35 + j × 60
• D. 35c - 60j

Q4. If 'a' denotes the side length of a regular pentagon, the formula for its perimeter is

• A. 2a
• B. 3a
• C. 4a
• D. 5a

Q5. Priya writes an expression for 'a number increased by 5'. If she uses the letter d for the number, her expression should be

• A. d + 5
• B. 5 - d
• C. 5d
• D. d - 5

Q6. Figure it Out Q5(c) asks for the expression for '2 less than 13 times a number'. If d is the number, the expression is

• A. 2 - 13d
• B. 13d - 2
• C. 13 - 2d
• D. 2d - 13

Q7. Which expression represents '13 less than 2 times a number d'?

• A. 13 - 2d
• B. 2 - 13d
• C. 13d - 2
• D. 2d - 13

Q8. Munirathna has a 20 m long pipe. He joins another pipe of length 'k' metres to it. The expression for the combined length, in metres, is

• A. 20k
• B. k - 20
• C. 20 + k
• D. 20 / k

Q9. Venkatalakshmi's flour mill takes 10 seconds to start. After it runs, each kg of grain takes 8 seconds to grind. Which expression gives the time to grind y kg of grain from off?

• A. 10 + 8 × y
• B. 10 × 8 + y
• C. (10 + 8) × y
• D. 10 × 8 × y

Q10. 5m stands for 5 × m. What is the value of the expression 5m + 3 when m = 2?

• A. 10
• B. 13
• C. 16
• D. 25

Q11. Using Ketaki's total-cost expression c × 35 + j × 60, what amount should a buyer pay for 7 coconuts and 4 kg jaggery?

• A. Rs 380
• B. Rs 425
• C. Rs 485
• D. Rs 650

Q12. A student writes: 'If d = 6, then 3d = 36'. What is the mistake in this simplification?

• A. There is no mistake — 3d = 36 is correct
• B. The student forgot to subtract 6
• C. The student should have divided 3 by 6
• D. 3d means 3 × d, so the value is 3 × 6 = 18, not 36

Q13. In the term 7k, the number 7 written in front of the letter k tells us

• A. How many times 7 must be added
• B. How many times k must be added — k is added 7 times
• C. That 7 should be subtracted from k
• D. That k must be divided by 7

Q14. Example 5 simplifies 5c + 3c + 10c using the distributive property. What is its simplest form?

• A. 18c
• B. 150c
• C. 18 + c
• D. c³

Q15. Simplify the expression p + q - (p + q) using bracket rules.

• A. 2p + 2q
• B. p - q
• C. 0
• D. 2(p + q)