Question Detail
Which among following is not a prime number ?
- 97
- 33
- 45
- 72
Answer: Option A
1. Difference between a two-digit number and the number obtained by interchanging the two digits is 36, what is the difference between two numbers
- 2
- 4
- 8
- 12
Answer: Option B
Explanation:
Let the ten digit be x, unit digit is y.
Then (10x + y) - (10y + x) = 36
=> 9x - 9y = 36
=> x - y = 4.
2. A number is doubled and 9 is added. If resultant is trebled, it becomes 75. What is that number
- 8
- 10
- 12
- 14
Answer: Option A
Explanation:
=> 3(2x+9) = 75
=> 2x+9 = 25
=> x = 8
3. if the sum of \begin{aligned} \frac{1}{2} \end{aligned} and \begin{aligned} \frac{1}{5} \end{aligned} of a number exceeds \begin{aligned} \frac{1}{3} \end{aligned} of the number by \begin{aligned} 7\frac {1}{3} \end{aligned}, then number is
- 15
- 20
- 25
- 30
Answer: Option B
Explanation:
Seems a bit complicated, isnt'it, but trust me if we think on this question with a cool mind then it is quite simple...
Let the number is x,
then, \begin{aligned} (\frac{1}{2}x + \frac{1}{5}x) - \frac{1}{3}x = \frac{22}{3} \end{aligned}
\begin{aligned}
=> \frac{11x}{30} = \frac{22}{3}
\end{aligned}
\begin{aligned}
=> x = 20
\end{aligned}
4. If one third of one fourth of number is 15, then three tenth of number is
- 34
- 44
- 54
- 64
Answer: Option C
Explanation:
Let the number is x,
\begin{aligned}
\frac{1}{3} of\frac{1}{4} * x = 15
\end{aligned}
\begin{aligned}
=> x = 15\times 12 = 180
\end{aligned}
\begin{aligned}
=> so \frac{3}{10} \times x = \frac{3}{10} \times 180 = 54
\end{aligned}
5. Sum of a rational number and its reciprocal is 13/6. Find the number
- 2
- 3/2
- 4/2
- 5/2
Answer: Option B
Explanation:
\begin{aligned} => x + \frac{1}{x} = \frac{13}{6} \end{aligned}
\begin{aligned} => \frac{x^2+1}{x} = \frac{13}{6} \end{aligned}
\begin{aligned} => 6x^2-13x+6 = 0 \end{aligned}
\begin{aligned} => 6x^2-9x-4x+6 = 0 \end{aligned}
\begin{aligned} => (3x-2)(2x-3) \end{aligned}
\begin{aligned} => x = 2/3 or 3/2 \end{aligned}