A certain amount of mixture contains milk and water in the ratio of 4 : 1.If 10 liters of this mixture is replaced by 10 liters of water, then the resultant ratio becomes 2 : 3.How much pure milk was originally there in the mixture at first.
1). 8 liters
2). 10 liters
3). 12 liters
4). 16 liters
Let the volume of water be = x
Then, volume of milk = 4x
Volume of Mixture replaced = 10 liters
Volume of water added = 10 liters
Volume of milk replaced = (4/5) × 10 = 8 liters
Volume of water replaced = 10 – 8 = 2 liters
Ratio of milk to water when mixture is replaced by 10 liters of water = 2 : 3
Initial, volume of milk = $(\frac{{4{\rm{x}} - 8}}{{{\rm{x}} - 2 + 10}} = \frac{2}{3})$
⇒ 12x – 24 = 2x + 16
⇒ 10x = 24 + 16
⇒ x = 40/10 = 4
∴ Volume of milk initially = 4 × 4 = 16 liters
∴ The initial volume of milk is 16 liters
3. Which of the following number should be added to 28614 so that 89 divides the result exactly?
4. What will come in place of question mark '?' in the following number series? 1, 4, 27, 16, 125, ?
8. What should come in place of question mark ‘?’ in the following number series? 15, 31, 45, 61, ?