Page 129 - NUMINO Challenge_A2

Answer
Key

Problem solving

1 To build streetlights that are 8 m apart on a road that is 80 m long, there will be

80 8 10 intervals between two adjacent streetlights.
Therefore, the number of streetlights is (Number of Intervals) 1 10 1 11 streetlights.

2 To build benches that are 10 m apart around a pond with a perimeter of 200 m, there will

be 200 10 20 intervals between two adjacent benches.
Number of Benches Number of Intervals 20 benches
Since 4 people can sit on 1 bench, a total of 20 4 80 people can sit on all the benches.

10. Solving by Drawing

Investigate A Snail that Fell into a Well Spread of Water Lilies

Height (m) 1st Day 2nd Day 3rd Day 4th Day
10
The water lilies covered half of the pond on the
5 3rd day

1
0 1 2 3 4 5 6 7 Days

It is not correct because on the 7th day, the snail
has already reached the top of the well during
the day.

Type Study Magic Flowers

1 The number of the magic flowers doubles everyday. Since the surface of the water was
completely covered on the 10th day, the surface was half-covered on the 9th day.

10th Day or
Answers will vary. 9th Day

24 NUMINO Challenge A2