NCERT Solutions Ganita Prakash (Part 1) Chapter 1 .4 Exact and Approximate Values — In-text Questions

Book page 101 Updated on2026-09-05

Q1.
What do you think of this conversation? Have you read or heard such headlines or statements? (“1 lakh people visited the book fair.” “If I had not gone, they would have written 99,999 people visited the book fair last week.”)
Answer

The joke is that the headline number was never meant to be exact — it is a rounded figure.

Why it happens: “1 lakh people visited the book fair” means about a lakh — it could be 97,400 or 1,02,600. One person more or less cannot change a rounded number. The boy is treating an approximate value as if it were an exact count, which is why the statement sounds funny.

Headlines of this kind are everywhere:

  • “Over 50,000 devotees at the temple on Ekadashi.”
  • “Nearly 1 crore people watched the match.”
  • “About 2 lakh vehicles cross the bridge every day.”
Tip: Words like about, nearly, over, around, approximately are the signal that the number has been rounded. When exactness matters — a bank balance, an exam mark, a train number — those words never appear.
Q2.
Think and share situations where it is appropriate to (a) round up, (b) round down, (c) either rounding up or rounding down is okay and (d) when exact numbers are needed.
Answer

Round the way that keeps you safe from a shortfall.

SituationExampleWhy
(a) Round upA school with 732 people orders 750 sweets; buying chairs for 118 guests → order 125Running short is worse than having a little extra
(b) Round downA shopkeeper says an item costing ₹470 is “around ₹450”; a bag holds 27 kg → “about 25 kg”A modest claim is safer than an exaggerated one
(c) Either is fineDistance from Delhi to Jaipur (268 km) → “about 270 km”; population of a cityOnly a rough idea of size is needed
(d) Exact numbersMoney in a bank account, marks in an exam, votes counted, a phone number, medicine doseEven a difference of 1 changes the meaning completely
Why it happens: Rounding up is used when a shortage causes trouble (food, chairs, tickets, cement bags). Rounding down is used when over-promising causes trouble (a price quote, a time estimate you must beat). And where the number itself is the answer — money, marks, counts — no rounding is allowed at all.
Try This: Bappi dialled “the rounded off number” for railway enquiry. Why is that a mistake? Because 139 is an exact helpline number — rounding it to 140 reaches nobody.
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