Page 134 - NUMINO Challenge_A2

2 Make a table and work backwards.

Sophie gave Amy the same number Sophie Amy
of chocolate bars that 28 10
Amy already has.
18 20
Amy gave 1 chocolate bar back to
Sophie. 19 19

Therefore, Sophie had 28 chocolate bars at the start.

Creative Thinking

1 Anna placed 8 stones, so there are 7 intervals in all. Dan placed 13 stones, so there are

12 intervals in all. Each interval in Anna's arrangement is 5 cm, so the length of the line
she made is 5 7 35 cm. Each interval in Dan's arrangement is 3 cm, so the length of
the line he made is 3 12 36 cm.
Therefore, Dan’s line is longer.

2 When five pictures are hung on the wall, there are 4 intervals between the pictures. Since

there are 2 intervals between the pictures on both ends and the edges of the wall, there
are 6 intervals altogether. The picture is 10 5 50 cm wide, so the total length of all the
intervals is 80 50 30 cm.
The total length of all the intervals should be divided into 6 equal lengths. Therefore, the
pictures should be hung every 30 6 5 cm apart.

3 Ryan drinks 9 bottles of juice. There will be 9 empty bottles.

Trade in 9 empty bottles for 3 new bottles of juice.
Ryan drinks 3 bottles of juice. There will be 3 empty bottles.
Trade in 3 empty bottles for 1 new bottle of juice.
Ryan drinks 1 bottle of juice.
Therefore, the greatest number of bottles of juice Ryan can get is 9 3 1 13 bottles.

29Answer Key