PSLE
Sabrina baked a total of 49 large and small cakes in the ratio of 5 : 2. She decorated each cake with some cranberries in the ratio of 7 : 4. She used a total of 420 cranberries to decorate all the small cakes and 4 large cakes.

1. How many small cakes did Sabrina bake?
2. What was the number of cranberries used to decorate all the small cakes?
3. How many more cranberries did Sabrina need to decorate the remaining large cakes?

(a)
Fraction of the cakes that were large ones = ⁵_{5 + 2} = ⁵₇

Number of large cakes
= ⁵₇ x 49
= 35

Number of small cakes
= 49 - 35
= 14

	Large cakes	Small cakes	Total
Number	4	14
Value	7 u	4 u
Total value	28 u	56 u	84 u

(b)
Number of cranberries used to decorate 4 large cakes and 14 small cakes
= 28 u + 56 u
= 84 u

84 u = 420

1 u = 420 ÷ 84 = 5

Number of cranberries used to decorate all the small cakes
= 56 u
= 56 x 5
= 280

(c)
Number of cranberries to decorate one large cake
= 7 u
= 7 x 5
= 35

Number of remaining large cakes that were decorated yet
= 35 - 4
= 31

Number of more cranberries that Sabrina needed to decorate the remaining large cakes
= 31 x 35
= 1085

Answer(s): (a) 14; (b) 280; (c) 1085