In a mixture of milk and water, the proportion of water by weight was 75%. If in the 60 gm mixture 15 gm of water was added, what would be the percentage of water ?

Answer: Option E

Weight of water in 60 gm mixture :
= 75% of 60 gm
= $$\left(\frac{75}{100}\times 60\right)$$   gm
= 45 gm
Weight of water in 75 gm mixture :
= (45 + 15) gm
= 60 gm
∴ Required percentage :
= $$\left(\frac{60}{75}\times 100\right)$$   %
= 80%