Page 167 - NUMINO Challenge_B2
P. 167
Answer
Key
4 36 16 52 minutes. Creative Thinking p.126~p.127
5 The log would be cut into 300 50 6 pieces. 1 The total number of students is equal to the
To cut the log into 6 pieces, you cut the log
6 1 5 times and took a break 5 1 4 times. difference in the numbers of students that are
It took 4 minutes to cut the log once; therefore, sitting directly across from each other times 2.
it took 4 5 20 minutes to cut the log 5 times. Since the 9th student and 35th student are facing
It took a 2-minute break 4 times; therefore, it each other, there are (35 9) 2 52 students in
took a break for 2 4 8 minutes. Therefore, it Ryan's class.
takes 20 8 28 minutes to cut the log.
2 When the streetlights are installed on one side
Problem solving
of a bridge at regular intervals, (the number of
1 When Anna cuts the sausage into 1-cm pieces, streetlights) (the number of Intervals) 1. Since
streetlights are being installed every 30 m on
she gets 15 1 15 pieces. To cut the sausage one side of a bridge, there will be 300 30 10
into 15 pieces, Anna needs to cut 15 1 14 intervals and 10 1 11 streetlights. Therefore,
times and take a break 14 1 13 times. Since it 22 streetlights are needed in total. Since a
takes 2 seconds to cut the sausage once, it will phone needs to be installed every 15 m
take 2 14 28 seconds to cut 14 times. The between each interval, 10 phones need to be
break time is 3 seconds; therefore, Anna takes a installed on one side. Therefore, 20 phones are
break for 3 13 39 seconds. Therefore, it will needed in total.
take Anna 28 39 67 seconds.
3 When 15 pieces of tape are placed together,
2 It takes 40 seconds to walk from the 1st floor to
there are 14 parts that overlap, and the total
the 5th floor; therefore, it takes 40 4 10 length of the overlapped parts is 14 2 28 cm.
seconds to walk up one floor. To reach the 25th Since the length of the entire piece of tape is
floor, Mark will need to go up 24 flights of stairs. 167 cm, it should be 167 28 195 cm when
Therefore, it will take him 10 24 240 seconds parts of the 15 pieces are not overlapped. There
without taking a break. Since Mark will not need are 15 pieces of tape; therefore, the length of
to take a break on the last floor, he takes a each piece is 195 15 13 cm.
break 24 1 23 times. The total break time is 8
4 When a 150-m long pipe is cut into 5-m pieces,
23 184 seconds. Therefore, it will take Mark
240 184 424 seconds, which is there will be 150 5 30 pieces.
7 minutes and 4 seconds, to reach the 25th floor. (the number of cuts) (the number of Pieces) 1
and (the number of breaks) (the number of
cuts) 1. Therefore, to cut into 30 pieces, Eric
needs to cut the pipe 30 1 29 times and take
a break 29 1 28 times. It takes 4 minutes to
cut once, so it will take 4 29 116 minutes in
total. Eric takes a 1-minute break; therefore, he
will take 1 28 28 minutes in total. Therefore,
it will take 116 28 144 minutes to cut the
entire pipe.
NUMINO Challenge B2
Key
4 36 16 52 minutes. Creative Thinking p.126~p.127
5 The log would be cut into 300 50 6 pieces. 1 The total number of students is equal to the
To cut the log into 6 pieces, you cut the log
6 1 5 times and took a break 5 1 4 times. difference in the numbers of students that are
It took 4 minutes to cut the log once; therefore, sitting directly across from each other times 2.
it took 4 5 20 minutes to cut the log 5 times. Since the 9th student and 35th student are facing
It took a 2-minute break 4 times; therefore, it each other, there are (35 9) 2 52 students in
took a break for 2 4 8 minutes. Therefore, it Ryan's class.
takes 20 8 28 minutes to cut the log.
2 When the streetlights are installed on one side
Problem solving
of a bridge at regular intervals, (the number of
1 When Anna cuts the sausage into 1-cm pieces, streetlights) (the number of Intervals) 1. Since
streetlights are being installed every 30 m on
she gets 15 1 15 pieces. To cut the sausage one side of a bridge, there will be 300 30 10
into 15 pieces, Anna needs to cut 15 1 14 intervals and 10 1 11 streetlights. Therefore,
times and take a break 14 1 13 times. Since it 22 streetlights are needed in total. Since a
takes 2 seconds to cut the sausage once, it will phone needs to be installed every 15 m
take 2 14 28 seconds to cut 14 times. The between each interval, 10 phones need to be
break time is 3 seconds; therefore, Anna takes a installed on one side. Therefore, 20 phones are
break for 3 13 39 seconds. Therefore, it will needed in total.
take Anna 28 39 67 seconds.
3 When 15 pieces of tape are placed together,
2 It takes 40 seconds to walk from the 1st floor to
there are 14 parts that overlap, and the total
the 5th floor; therefore, it takes 40 4 10 length of the overlapped parts is 14 2 28 cm.
seconds to walk up one floor. To reach the 25th Since the length of the entire piece of tape is
floor, Mark will need to go up 24 flights of stairs. 167 cm, it should be 167 28 195 cm when
Therefore, it will take him 10 24 240 seconds parts of the 15 pieces are not overlapped. There
without taking a break. Since Mark will not need are 15 pieces of tape; therefore, the length of
to take a break on the last floor, he takes a each piece is 195 15 13 cm.
break 24 1 23 times. The total break time is 8
4 When a 150-m long pipe is cut into 5-m pieces,
23 184 seconds. Therefore, it will take Mark
240 184 424 seconds, which is there will be 150 5 30 pieces.
7 minutes and 4 seconds, to reach the 25th floor. (the number of cuts) (the number of Pieces) 1
and (the number of breaks) (the number of
cuts) 1. Therefore, to cut into 30 pieces, Eric
needs to cut the pipe 30 1 29 times and take
a break 29 1 28 times. It takes 4 minutes to
cut once, so it will take 4 29 116 minutes in
total. Eric takes a 1-minute break; therefore, he
will take 1 28 28 minutes in total. Therefore,
it will take 116 28 144 minutes to cut the
entire pipe.
NUMINO Challenge B2
