Question : A water tap fills a tub in '$p$' hours and a sink at the bottom empties it in '$q$' hours. If $p < q$, both tap and sink are open, and the tank is filled in '$r$' hours, then:
Option 1: $\frac{1}{r}$ = $\frac{1}{p}+\frac{1}{q}$
Option 2: $\frac{1}{r}$ = $\frac{1}{p}-\frac{1}{q}$
Option 3: $r = p + q$
Option 4: $r = p - q$
Latest: SSC CGL preparation tips to crack the exam
Don't Miss: SSC CGL complete guide
New: Unlock 10% OFF on PTE Academic. Use Code: 'C360SPL10'
Correct Answer: $\frac{1}{r}$ = $\frac{1}{p}-\frac{1}{q}$
Solution : Given: A water tap fills a tub in '$p$' hours and a sink at the bottom empties it in '$q$' hours where $p < q$. So, in 1 hour the tap will fill $\frac{1}{p}$ part of the tub. Also, in 1 hour the sink will empty $\frac{1}{q}$ part of the tub. Now, part of the tub that will fill in 1 hour with both of them opened = ($\frac{1}{p}-\frac{1}{q}$) Time taken to fill the whole tub = $\frac{1}{(\frac{1}{p}–\frac{1}{q})}$ hours, which is equal to $r$. Therefore, $\frac{1}{(\frac{1}{p}–\frac{1}{q})}$ = $r$ ⇒ $\frac{1}{r}$ = $\frac{1}{p}-\frac{1}{q}$ Hence, the correct answer is $\frac{1}{r}$ = $\frac{1}{p}-\frac{1}{q}$.
Candidates can download this ebook to know all about SSC CGL.
Answer Key | Eligibility | Application | Selection Process | Preparation Tips | Result | Admit Card
Question : If $P =\frac{96}{95\times97}, Q = \frac{97}{96\times98}$ and $R = \frac{1}{97}$, then which of the following is true?
Question : An inlet pipe can fill an empty tank in $4 \frac{1}{2}$ hours, while an outlet pipe drains a filled tank in $7 \frac{1}{5}$ hours. The tank is initially empty, and the two pipes are alternately opened for an hour each, till the tank is filled, starting with the
Question : A tap can fill a tank in $5 \frac{1}{2}$ hours. Because of a leak, it took $8 \frac{1}{4}$ hours to fill the tank. In how much time (in hours) will the leak alone empty 30% of the tank?
Question : The value of $ \frac{(p-q)^3+(q-r)^3+(r-p)^3}{12(p-q)(q-r)(r-p)}$, where $p \neq q \neq r$, is equal to:
Question : There are 3 taps A, B, and C in a tank. These can fill the tank in 10 hours, 20 hours, and 25 hours, respectively. At first, all three taps are opened simultaneously. After 2 hours, tap C is closed and A and B keep running. After 4 hours from the beginning, tap B is also
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile