1 . | Answer : Option C | Explanation : | Efficiency ratio of Monu and Sonu = 100:80 = 5:4 ∴ Time taken will be as = 4:5 (more efficient takes less time) $4\over5$=18\x x= $5x 18\over4$=22.5days | | | 2 . | Answer : Option B | Explanation : | We have basic formula: men x days = constant i.e. M1D1 = M2D2 (M = men, D = days) or, Directly, $8\times(42-6)\over6$=48
| | | 3 . | Answer : Option C | Explanation : | | | | 4 . | Answer : Option D | Explanation : | = $72+6-4\over24$ = $72\over24$ = $37\over12$ | | | 5 . | Answer : Option D | Explanation : | This is on combinations, since 1 boy is always there, remaining 1 boy will be selected from 11 and $^{11}C_1$ ways and similarly, girls in $^{15}C_1$ ways and total selections will be $^{28}C_4$ ∴ Required probability = ${ ^{11}C_1 \times ^{15}C_1 \over ^{28}C_4}$ | | | 6 . | Answer : Option A | Explanation : | Since highest remains the same, only base area will affect volume ∴ Required increase = 10 + 10 + $10 \times 10\over100$ = 21% | | | 7 . | Answer : Option D | Explanation : | | | | 8 . | Answer : Option B | Explanation : | $70\over100$ x = 3.5, i.e. x = 5 (II): $y^ 2 + 6y + 8 = 0$. i.e. $y^ 2 + 4y + 2y + 8 = 0$ i.e. y (y + 4) + 2 (y + 4) = 0, i.e. y = - 2, y = -4 Thus, x = 5 > y = -2, -4 | | | 9 . | Answer : Option A | Explanation : | II.$2y^2$+3y-9=0 Dividing by 2, we get(I). Thus, x=y | | | 10 . | Answer : Option C | Explanation : | Solving simultaneously, X = -3, y = -2 i.e. y = -2 > x = - 3 | | | |

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