Page 166 - NUMINO Challenge_B2
P. 166
14 Streetlights and Logs p.120~p.121 Problem solving
Example 2, 2 3, 5, 2, 3, 4, 1, 3 1 There are (6 1) 6 30 stones that are placed
2 30, 13, 2, 34
around a regular hexagon. To count the number
TryItAgain The total number of flowers was equal to of stones on each side of the hexagon without
twice the difference in the numbers of the counting the same stone twice, you need to
flowers that were planted directly across divide the stones into groups of 30 3 10
from each other. Since the 8th flower and the stones. Therefore, 10 1 11 stones are placed
21st flower needed to be planted directly on each side.
across from each other, Alice planted
(21 8) 2 26 flowers. 2 When 12 pieces of tape are placed without any
Example 1, 8, 8, 9, 9, 18 1, 8, 8, 16 overlapping parts, the total length is 15 12
180 cm. Since the overlapped part is 1 cm, the
TryItAgain To cut a log into 3 pieces, you need to cut it total length reduces by 1 cm whenever the
twice. Since it takes 10 minutes to cut it, it pieces of tape overlap. Therefore, since there
takes 5 minutes to cut a log once. To cut a are 11 overlapped parts, the total length is
log into 9 pieces, you need to cut it 8 times; 180 11 169 cm.
therefore, it will take 5 8 40 minutes.
Type 14-2 Taking Breaks while Cutting Logs p.124~p.125
1 500 50 10 pieces
2 Number of Number of Number of
Type 14-1 Simplifying to Solve Problems p.122~p.123 Log Pieces Cuts Breaks
1 When the flowers are planted as shown in the 21 0
picture, the flower that is on each vertex is
counted twice; therefore, you need to subtract 3 32 1
flowers.
43 2
2
54 3
23 33 43 From the chart you can notice that
6 flowers (Number of Cuts) (Number of Log Pieces) 1
(Number of Breaks) (Number of Cuts) 1.
Therefore, to cut 10 pieces you would need to
cut the log 9 times and take a break 8 times.
9 flowers 12 flowers
3 (25 1) 3 72 flowers 3 Since it took 4 minutes to cut the log once, it
4 72 4 18 flowers took 4 9 36 minutes to cut the log 9 times.
5 18 1 19 flowers You took a 2-minute break 8 times; therefore,
the break time is 2 8 16 minutes.
Answer Key
Example 2, 2 3, 5, 2, 3, 4, 1, 3 1 There are (6 1) 6 30 stones that are placed
2 30, 13, 2, 34
around a regular hexagon. To count the number
TryItAgain The total number of flowers was equal to of stones on each side of the hexagon without
twice the difference in the numbers of the counting the same stone twice, you need to
flowers that were planted directly across divide the stones into groups of 30 3 10
from each other. Since the 8th flower and the stones. Therefore, 10 1 11 stones are placed
21st flower needed to be planted directly on each side.
across from each other, Alice planted
(21 8) 2 26 flowers. 2 When 12 pieces of tape are placed without any
Example 1, 8, 8, 9, 9, 18 1, 8, 8, 16 overlapping parts, the total length is 15 12
180 cm. Since the overlapped part is 1 cm, the
TryItAgain To cut a log into 3 pieces, you need to cut it total length reduces by 1 cm whenever the
twice. Since it takes 10 minutes to cut it, it pieces of tape overlap. Therefore, since there
takes 5 minutes to cut a log once. To cut a are 11 overlapped parts, the total length is
log into 9 pieces, you need to cut it 8 times; 180 11 169 cm.
therefore, it will take 5 8 40 minutes.
Type 14-2 Taking Breaks while Cutting Logs p.124~p.125
1 500 50 10 pieces
2 Number of Number of Number of
Type 14-1 Simplifying to Solve Problems p.122~p.123 Log Pieces Cuts Breaks
1 When the flowers are planted as shown in the 21 0
picture, the flower that is on each vertex is
counted twice; therefore, you need to subtract 3 32 1
flowers.
43 2
2
54 3
23 33 43 From the chart you can notice that
6 flowers (Number of Cuts) (Number of Log Pieces) 1
(Number of Breaks) (Number of Cuts) 1.
Therefore, to cut 10 pieces you would need to
cut the log 9 times and take a break 8 times.
9 flowers 12 flowers
3 (25 1) 3 72 flowers 3 Since it took 4 minutes to cut the log once, it
4 72 4 18 flowers took 4 9 36 minutes to cut the log 9 times.
5 18 1 19 flowers You took a 2-minute break 8 times; therefore,
the break time is 2 8 16 minutes.
Answer Key
