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NCERT Solutions for Class 5th Maths Chapter 5 Sheena and Jennifer organise a 3-km race — Kilometre Race

Book page 60 Updated on2026-09-19

Q1.
Water stations are to be arranged after every 500 m. How many water stations must be set up? At what positions from the starting point will these water stations be placed?
Answer

6 water stations. They go at 500 m, 1,000 m, 1,500 m, 2,000 m, 2,500 m and 3,000 m from the start.

Work it out step by step.

  1. Change the race into metres. The race is 3 km. Since 1 km = 1,000 m, the race is 3 × 1,000 = 3,000 m.
  2. Count in jumps of 500 m. 500, 1,000, 1,500, 2,000, 2,500, 3,000.
  3. Count the jumps. That is 6 marks.
3 km = 3 × 1,000 = 3,000 m
3,000 ÷ 500 = 6 water stations
Positions: 500 m, 1 km, 1 km 500 m, 2 km, 2 km 500 m, 3 km
Start 500 m1 km1.5 km 2 km2.5 km3 km Six blue dots = six water stations, one after every 500 m.
The 3,000 m track with a water station after every 500 m.
Why we divide: The question asks how many 500 m pieces fit inside 3,000 m. Dividing is exactly the way to ask that question. 3,000 ÷ 500 = 6.
Think about it: The sixth station is right at the finish line, where the runners will want water most. If a school decides not to put one at the finish, then only 5 stations are needed. Say which choice you made when you answer.
Q2.
Children need to stand at an interval of 300 m to direct the runners. How many children are needed? At what positions from the starting point will the children be standing?
Answer

10 children. They stand at 300 m, 600 m, 900 m, 1,200 m, 1,500 m, 1,800 m, 2,100 m, 2,400 m, 2,700 m and 3,000 m.

  1. The race is 3,000 m long (3 km = 3 × 1,000).
  2. Each gap between two children is 300 m.
  3. Ask how many 300 m gaps fit in 3,000 m. Divide: 3,000 ÷ 300 = 10.
  4. Write the positions by counting in 300s.
3,000 ÷ 300 = 10 children
Positions: 300 m, 600 m, 900 m, 1,200 m, 1,500 m,
1,800 m, 2,100 m, 2,400 m, 2,700 m, 3,000 m
Why 10 and not 11: We are counting the marks along the track, starting 300 m after the start line. If Sheena also wants one child standing at the start line itself, then 11 children are needed. Read the words carefully — "at an interval of 300 m" means the first child is 300 m along.
Check it yourself: 10 children × 300 m = 3,000 m. The last child is exactly at the finish line ✓
Q3.
Red and blue flags are to be placed alternately at every 50 m. How many red and blue flags are needed till the finish line?
Answer

60 flags in all — 30 red and 30 blue.

  1. Find how many flag positions there are. The race is 3,000 m and a flag stands every 50 m. 3,000 ÷ 50 = 60 positions.
  2. Now share these 60 positions between two colours. Alternately means red, blue, red, blue, … all the way.
  3. Split 60 into two equal groups. 60 ÷ 2 = 30.
3,000 ÷ 50 = 60 flag positions
60 ÷ 2 = 30 red flags and 30 blue flags
Total = 30 + 30 = 60 flags
50 m100 m150 m200 m 250 m300 m350 m400 m Red, blue, red, blue … the pattern repeats every 100 m, so thecolours share equally. The first 400 m of the track
Alternating flags. In every 100 m there is one red flag and one blue flag.
Why the two colours come out equal: The pattern red-blue repeats as one pair every 100 m. The track is 3,000 m, which holds 30 such pairs. Each pair has one red and one blue, so there are 30 of each.
Check it yourself: 30 pairs × 100 m = 3,000 m ✓ And 30 + 30 = 60 flags, which matches 3,000 ÷ 50 = 60 ✓
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