NCERT Solutions Ganita Prakash (Part 1) Chapter 8 –177Section 8.1 Multiplication of Fractions — Figure it Out

Book page 176 Updated on2026-09-05

Q1.

Tenzin drinks ¹⁄₂ glass of milk every day. How many glasses of milk does he drink in a week? How many glasses of milk did he drink in the month of January?

Answer

Multiply the daily amount by the number of days.

In a week (7 days) = 7 × 1/2 = 7/2 = 3 1/2 glasses
January has 31 days
In January = 31 × 1/2 = 31/2 = 15 1/2 glasses

Why it happens: two half-glasses make one full glass. Seven halves are three full glasses and one half left; thirty-one halves are fifteen full glasses and one half left.

Q2.

A team of workers can make 1 km of a water canal in 8 days. So, in one day, the team can make ___ km of the water canal. If they work 5 days a week, they can make ___ km of the water canal in a week.

Answer

One kilometre of work is spread equally over 8 days.

Work in 1 day = 1 ÷ 8 = 1/8 km
Work in 5 days = 5 × 1/8 = 5/8 km

Days worked	Canal made
1	1/8 km
5 (one week)	5/8 km
8	8/8 = 1 km

Check it yourself: 5/8 km = 625 m — a little more than half a kilometre in a 5-day week.

Q3.

Manju and two of her neighbours buy 5 litres of oil every week and share it equally among the 3 families. How much oil does each family get in a week? How much oil will one family get in 4 weeks?

Answer

Five litres shared equally by 3 families.

Oil per family in 1 week = 5 ÷ 3 = 5/3 litres = 1 2/3 litres
In 4 weeks = 4 × 5/3 = 20/3 = 6 2/3 litres

Why it happens: cut every litre into 3 equal parts. There are 5 × 3 = 15 one-third parts, and 15 ÷ 3 = 5 parts for each family — that is ⁵⁄₃ litres.

Q4.

Safia saw the Moon setting on Monday at 10 pm. Her mother, who is a scientist, told her that every day the Moon sets ⁵⁄₆ hour later than the previous day. How many hours after 10 pm will the moon set on Thursday?

Answer

Monday to Thursday is 3 days, so the delay builds up three times.

Delay = 3 × 5/6
= 15/6
= 5/2
= 2 1/2 hours after 10 pm

So the Moon sets at about 12:30 am (past midnight).

Tip: Monday → Tuesday is 1 delay, Tuesday → Wednesday is 2, Wednesday → Thursday is 3. Count the gaps between days, not the days.

Q5.

Multiply and then convert it into a mixed fraction: (a) 7 × ³⁄₅ (b) 4 × ¹⁄₃ (c) ⁹⁄₇ × 6 (d) ¹³⁄₁₁ × 6

Answer

Multiply the whole number into the numerator, then split off the whole part.

Question	Product	Mixed fraction
(a) 7 × 3/5	21/5	4 1/5
(b) 4 × 1/3	4/3	1 1/3
(c) 9/7 × 6	54/7	7 5/7
(d) 13/11 × 6	78/11	7 1/11

21 ÷ 5 = 4 remainder 1 → 4 1/5
54 ÷ 7 = 7 remainder 5 → 7 5/7
78 ÷ 11 = 7 remainder 1 → 7 1/11

Why it works: the quotient tells you how many wholes are hidden inside the improper fraction and the remainder is the fifths (or sevenths, or elevenths) that are left over.

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