$A$ person distributes his pens among four friends $A, B, C$ and $D$ in the ratio $\frac{1}{3}: \frac{1}{4}: \frac{1}{5}: \frac{1}{6}$. What is the minimum number of pens that the person should have?

In an army selection process,the ratio of selected to unselected candidates was $5:1$. If $100$ fewer candidates had applied and $20$ fewer had been selected,the ratio of selected to unselected candidates would have been $6:1$. How many candidates had applied for the process?

The ratio of ages between $A$ and $B$ is $6: 5$ and the age of each $C$ and $D$ is $\frac{9}{10}$ times that of $B$. The age of $F$ is less than $A$ but greater than $B$. The ratio of ages between $B$ and $E$ is $2: 3$. Also,the age of $A$ is $3 \text{ years}$ less than $E$. What is the ratio of the ages of $A$ and $F$ if all the ages are integers?

What is the fourth proportional to $189, 273$ and $153$?

$A$ and $B$ earn in the ratio $2:1$. They spend in the ratio $5:3$ and save in the ratio $4:1$. If the total monthly savings of both $A$ and $B$ are ₹ $5,000$,the monthly income of $B$ is (in ₹): (in $,000$)

If $A: B = \frac{1}{2}: \frac{3}{8}$,$B: C = \frac{1}{3}: \frac{5}{9}$ and $C: D = \frac{5}{6}: \frac{3}{4}$,then the ratio $A: B: C: D$ is