Page 124 - NUMINO Challenge_B2

Basic Concepts Trees and Logs

Find the rules for solving the problems of planting trees and cutting logs.

Planting trees: Trees must be planted at the Interval Interval
beginning and the end of the road.
(Number of Trees) (Number of Intervals) 1

Cutting Logs: When logs are cut at regular intervals,
they are not cut at the beginning and end.
(Number of Cuts) (Number of Log Pieces) 1

Example There is a road that is 80 m long. Palm trees are planted at every
10 m including the beginning and the end of the road. One apple
tree is planted between every two palm trees. How many palm
trees are planted? How many apple trees are planted? Note that
trees are planted on both sides of the road.

Class Notes

The number of trees planted on one side of the road is: Number of Trees Number of

Intervals . There are 80 10 Intervals when trees are planted every 10 m

along an 80-m road. Therefore, the number of palm trees on one side of the road is,

1 . There are 2 palm trees in total.

The picture on the right shows that apple trees are

planted between two palm trees, and each space between

the trees is 5 m. On either side of the road, there are

Intervals. Therefore, 2 apple trees are 5m 5m
planted in total. 10 m

Try It Again It takes 10 minutes to cut a log into 3 pieces. How long will it take
to cut a log into 9 pieces if it is cut at the same speed?

121Communication