NCERT Solutions Ganita Prakash (Part 1) Chapter 4 In-text Questions — The Notion of Letter-Numbers

Book page 83 Updated on2026-09-05

Q1.

Example 3: Ketaki prepares and supplies coconut-jaggery laddus. The price of a coconut is ₹35 and the price of 1 kg jaggery is ₹60. How much should she pay if she buys 10 coconuts and 5 kg jaggery?

Answer

Find the two costs separately and add them.

Cost of 10 coconuts = 10 × ₹35 = ₹350
Cost of 5 kg jaggery = 5 × ₹60 = ₹300
Total cost = ₹350 + ₹300 = ₹650

Q2.

How much should she pay if she buys 8 coconuts and 9 kg jaggery?

Answer

Same two steps, new numbers.

Cost of 8 coconuts = 8 × ₹35 = ₹280
Cost of 9 kg jaggery = 9 × ₹60 = ₹540
Total = ₹280 + ₹540 = ₹820

Tip: 8 × 35 is easy as 8 × 35 = 8 × 30 + 8 × 5 = 240 + 40 = 280.

Q3.

Write an algebraic expression to find the total amount to be paid for a given number of coconuts and quantity of jaggery.

Answer

Let c be the number of coconuts and j the number of kilograms of jaggery.

Quantity needed	Relationship	Expression
Cost of coconuts	Number of coconuts × 35	c × 35
Cost of jaggery	Number of kgs of jaggery × 60	j × 60

Total amount = Cost of coconuts + Cost of jaggery
c × 35 + j × 60

Why it happens: The rates 35 and 60 never change; only the quantities c and j change. That is exactly what a formula is built to handle.

Q4.

Use this expression (or formula) to find the total amount to be paid for 7 coconuts and 4 kg jaggery.

Answer

Put c = 7 and j = 4.

c × 35 + j × 60
= 7 × 35 + 4 × 60
= 245 + 240
= ₹485

Q5.

Example 4: The perimeter of a square is 4 times the length of its side, written as 4 × q. What is the perimeter of a square with sidelength 7 cm? Use the expression to find out.

Answer

Put q = 7 in 4 × q.

Perimeter = 4 × q
= 4 × 7
= 28 cm

Why it happens: A square has 4 equal sides, so its boundary is the same length added 4 times: q + q + q + q = 4 × q.

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