Question : X can do a work in 3 days, Y can do three times the same work in 8 days, and Z can do five times the same work in 12 days. If they have to work together for 6 hours a day, then how much time will they take to complete the work?
Option 1: 4 hours
Option 2: 5 hours 20 minutes
Option 3: 4 hours 10 minutes
Option 4: 5 hours
Correct Answer: 5 hours 20 minutes
Solution : X can complete the work in 3 days. Y can do three times the same work in 8 days. Z does five times the same work in 12 days. Working hours per day = 6 hours Efficiency = $\frac{\text{Total work}}{\text{Total Time}}$ Let the total work be 1 unit. Time to complete 1 unit by X alone = 3 × 6 = 18 hours Time to complete the 3 units by Y alone = 8 × 6 = 48 hours Time to complete the 1 unit by Y alone = $\frac{48}{3}$ = 16 hours Time to complete the 5 units by Z alone = 12 × 6 = 72 hours Time to complete the 1 unit by Z alone = $\frac{72}{5}$hours Efficiency of X = $\frac{1}{18}$ units/hour Efficiency of Y = $\frac{1}{16}$ units/hour Efficiency of Z = $ \frac{5}{72}$ units/hour Combined efficiency of X, Y and Z $=\frac{1}{18} + \frac{1}{16}+ \frac{5}{72}=\frac{(8 + 9 + 10)}{144}=\frac{27}{144}$ units/hour Time to complete total work by X, Y and Z together = $\frac{1}{\frac{27}{144}}$= $\frac{144}{27}$ hours = $\frac{144}{27}×60$ = $320$ minutes = 5 hours 20 minutes Hence, the correct answer is 5 hours 20 minutes.
Result | Eligibility | Application | Selection Process | Cutoff | Admit Card | Preparation Tips
Question : A can do $\frac{4}{5}$th of a work in 20 days and B can do $\frac{3}{4}$th of the same work in 15 days. They work together for 10 days. C alone completes the remaining work in 1 day. B and C together can complete $\frac{3}{4}$th of the same work in:
Question : To do a certain task X would take 3 times as long as Y and Z together, and Z would take 4 times as long as Y and X together. Three of them together can complete the task in 10 days. How much time is taken by X and Z to complete the task?
Question : A and B together can do a certain work in $x$ days. Working alone, A and B can do the same work in ($x$ + 8) and ($x$ + 18) days, respectively. A and B together will complete $\frac{5}{6}$th of the same work in:
Question : What is $\frac{\left (x^{2}-y^{2} \right)^{3}+\left (y^{2}-z^{2} \right )^{3}+\left (z^{2}-x^{2} \right )^{3}}{\left (x-y \right)^{3}+\left (y-z \right )^{3}+\left (z-x \right)^{3}}?$
Question : Vipin can do a piece of work in 2 days; Vaibhav can do the same work in 3 days and Chirag can do the same work in 6 days. If they start working together, how many days will they take to complete the work?
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile