IBPS SO Prelims Exam Model Paper 3

Given
Ratio of gold and copper to make jewelry = 3 : 2
Mixture replace by copper = 20 gram
New ratio = 5 : 4
Formula used

Quantity‌of‌cheaper

Quantity‌of‌dearer

=

(Price‌of‌dearer−Average‌price)

(Average‌price−Price‌of‌cheaper)

Calculation
Let the amount of gold and copper in the initial mixture respectively = 3x gram and 2x gram.
Amount of gold in 20 grams of mixture =

3x

5x

× 20 = 12 grams
Amount of copper in 20 grams of mixture =

2x

5x

× 20 = 8 grams
According to the question
⇒

(3x–12)

(2x–8+20)

=

5

4

⇒ x = 54
The amount of gold in the initial mixture = 3x = 3 × 54 = 162
∴ The amount of gold in the initial mixture is 162.