GK Expert Team Solutions for Chapter: Practice Paper, Exercise 3: Set 1

A motorboat whose speed is $15 \mathrm{km}/\mathrm{hr}$ in still water goes $30 \mathrm{km}$ downstream and comes back in a total of $4 \mathrm{hrs}$ and $3 \min$. The speed of the stream (in $\mathrm{km}/\mathrm{hr}$) is:

Rohit invests an amount of $₹.24,200$ at the rate of $4\%$ p.a. for $6$years to obtain a simple interest. Later he invests the principal amount as well as the amount obtained as simple interest for another $4$years at the same rate of interest. What amount of simple interest will he obtain at the end of the last $4$ years?

A basket contains $4$red, $5$blue and $3$green marbles. If three marbles are picked at random, what is the probability that either all are green or all are red? 

A sample of '$p$' litre from a container having $112$litre mixture of milk and water containing milk and water in the ratio of $3:5$ respectively is replaced with pure milk so that the container will have milk and water in the ratio of $3:1$. What is the value of '$p$'?

Aman owned $950$ gold coins. All of which he distributed amongst his three daughters Lata, Anita, and Meeta. Lata gave $25$ gold coins to her husband, Anita donated $15$ gold coins and Meeta made jewellery out of $30$ gold coins. The new respective ratio of the coins left with them was $20:73:83$. How many gold coins did Anita receive from Aman?

A car travels a certain distance from A to town B at speed of $42$ km/hr and from B to town A at the speed of $48$ km/hr. What is the average speed of the car?

Present ages of Rohit and Rohan are in the ratio of $6:7$ respectively. Five years ago their ages were in the ratio of $5:6$ respectively. What is Rohit's present age?

A field is in the form of an equilateral triangle with side $600$ m. Three cows are tied to the three poles at the three vertices of this triangular field with ropes of length $100$ m, $200$ m and $300$ m respectively. What is the area of the field that they can graze?