Tao Nan School P5 SA2 2007 Math Q37

A book and 3 pens cost $11.25. The book cost twice as much as a pen. Find the cost of 4 books.

Solution

Book ----- 2 units
Pen ----- 1 unit

1 book + 3 pens ----- $11.25
2 units + 3 units ----- $11.25
5 units ----- $11.25
1 unit ----- $11.25 divided by 5 = $2.25

(4 books) 4 x 2 units ---- 8 units
8 units ----- 8 x $2.25 = $18

Answer: The cost of 4 books is $18.

Tao Nan School P5 SA2 2007 Math Q36

A baking machine can bake 20 muffins in 10 minutes. At this rate, how long does this machine take to bake 48 muffins?

Solution

Unit Method
20 muffins ----- 10 min
1 muffin ----- 10 min divided 20 = ½ min
48 muffins ----- ½ min x 48 = 24 minutes


Ratio Method
Muffins : Minutes
20 : 10
2 : 1
48 : 24

Answer: It takes 24 minutes to bake 48 muffins