RRB Group D 1 Dec 2025 Shift 1 Solved Paper

Concept:Percentage change in total cost is calculated by finding the net change divided by the initial total cost, multiplied by 100.Explanation:Let the cost of a TV be $100$ units.Then, the cost of a washing machine (WM) is $50\%$ less than the TV, so WM cost = $100 - 50\% \times 100 = 50$ units.The initial total cost for $8$ WMs and $4$ TVs = $(8 \times 50) + (4 \times 100) = 400 + 400 = 800$ units.The cost of WM increases by $83\%$.Change in total WM cost = $400 \times 83\% = 400 \times 0.83 = 332$ units (increase).The cost of TV decreases by $38\%$.Change in total TV cost = $400 \times (-38\%) = 400 \times (-0.38) = -152$ units (decrease).Net change in total cost = $332 + (-152) = 180$ units (increase).Percentage change = $\frac{180}{800} \times 100 = 22.5\%$ increase.Answer:Increase by $22.5\%$ (Option B).