In a collection of rare coins, there is one gold coin for every four non-gold coins. If 20 more gold coins are added to the collection, the ratio of the number of gold coins to that of non-gold coins will be 2 : 3. The total number of coins in the collection will now become ________.
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 80.
Let the initial number of gold coins = g
Let the initial number of non-gold coins = n
So, g/n = 1/4
⇒ n = 4g
Also, (g + 20)/n = 2/3
⇒ (g + 20)/(4g) = 2/3
⇒ 3g + 60 = 8g
⇒ 5g = 60
⇒ g = 12
⇒ n = 4g = 4 × 12 = 48
Total coins = (12 + 20) + 48 = 80
Therefore, the total number of coins in the collection will now become 80.