SSC CGL 20221)An alloy contains 40% of silver, 30% of copper, and 30% of nickel. How much silver (in kg) should be added to 25 kg of the alloy so that the new alloy contains 50% of silver?
5
In 25 kg alloy, there is 40% silver, 30% copper, 30% nickel
Thus,
Silver = 40% of 25kg = 10kg, Copper = 30% of 25kg = 7.5kg, nickel = 30% of 25kg = 7.5
Let x kg of silver be added in alloy to make silver 50% in the alloy
\({(10+x)100 \over 25+x} = 50\)
x = 5, hence silver added = 5 kg
SSC CGL 20222)80% and 90% pure acid solutions are mixed to obtain 20 litres of 87% pure acid solution. Find the quantity (in litres) of 80% pure acid solution taken to form the mixture.
6
SSC CGL 20223)A container contains 25 litre of milk. From this container, 5 litre of milk is taken out and replaced by water. This process is further repeated two times. How much milk is there in the container now?
12.8 litre
SSC CGL 20224)P and Q are two alloys of aluminum and copper. The ratios of aluminum and copper in P and Q are 5 ∶ 11 and 3 ∶ 5, respectively. If a third alloy is formed by mixing alloys P and Q in the ratio of 1 ∶ 3, then aluminum is what percentage (rounded off to the nearest integer) of the copper in the third alloy?
56 Percent
SSC CGL 20225)A can of water and milk mixture contains 60% milk. A part of this mixture is replaced by another mixture containing 50% milk and the percentage of milk was found to be 52%. The quantity of mixture replaced is:
\(4 \over 5\)