PSLE
Erika baked a total of 40 large and small cakes in the ratio of 7 : 3. She decorated each cake with some blueberries in the ratio of 7 : 3. She used a total of 497 blueberries to decorate all the small cakes and 5 large cakes.

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

(a)
Fraction of the cakes that were large ones = ⁷_{7 + 3} = ⁷₁₀

Number of large cakes
= ⁷₁₀ x 40
= 28

Number of small cakes
= 40 - 28
= 12

	Large cakes	Small cakes	Total
Number	5	12
Value	7 u	3 u
Total value	35 u	36 u	71 u

(b)
Number of blueberries used to decorate 5 large cakes and 12 small cakes
= 35 u + 36 u
= 71 u

71 u = 497

1 u = 497 ÷ 71 = 7

Number of blueberries used to decorate all the small cakes
= 36 u
= 36 x 7
= 252

(c)
Number of blueberries to decorate one large cake
= 7 u
= 7 x 7
= 49

Number of remaining large cakes that were decorated yet
= 28 - 5
= 23

Number of more blueberries that Erika needed to decorate the remaining large cakes
= 23 x 49
= 1127

Answer(s): (a) 12; (b) 252; (c) 1127