SSC CHSL 15 Nov 2025 Shift 1 Paper

Concept:Use the alligation rule to find the proportion in which two mixtures must be combined to achieve a target ratio.Explanation:First, find the fraction of milk in each mixture.Mixture 1: milk fraction = $3/(3+2) = 3/5$.Mixture 2: milk fraction = $7/(7+3) = 7/10$.Target mixture: milk fraction = $5/(5+3) = 5/8$.Apply alligation on the milk fractions:Take the difference between the target and each mixture fraction.Difference with mixture 1: $3/5 - 5/8 = (24-25)/40 = -1/40$.Difference with mixture 2: $5/8 - 7/10 = (50-56)/80 = -6/80$.Ignore the negative signs; the required ratio is the absolute values of these differences taken in cross order.Ratio of mixture 1 to mixture 2 = $\frac{6}{80} : \frac{1}{40}$.Simplify: $\frac{6}{80} = \frac{3}{40}$, and $\frac{1}{40} = \frac{1}{40}$. So ratio = $3:1$.Answer:The mixtures must be mixed in the ratio $3:1$. Option C.