Question Detail
What will be the LCM of 8, 24, 36 and 54
- 54
- 108
- 216
- 432
Answer: Option C
Explanation:
LCM of 8-24-36-54 will be
2*2*2*3*3*3 = 216
1. There are three numbers, these are co-prime to each other are such that the product of the first two is 551 and that of the last two is 1073. What will be the sum of three numbers :
- 80
- 82
- 85
- 87
Answer: Option C
Explanation:
As given the questions these numbers are co primes, so there is only 1 as their common factor.
It is also given that two products have the middle number in common.
So, middle number = H.C.F. of 551 and 1073 = 29;
So first number is : 551/29 = 19
Third number = 1073/29 = 37
So sum of these numbers is = (19 + 29 + 37) = 85
2. An electronic device makes a beep after every 60 sec. Another device makes a beep after every 62 sec. They beeped together at 10 a.m. The time when they will next make a beep together at the earliest, is
- 10:28 am
- 10:30 am
- 10:31 am
- None of above
Answer: Option C
Explanation:
L.C.M. of 60 and 62 seconds is 1860 seconds
1860/60 = 31 minutes
They will beep together at 10:31 a.m.
Sometimes questions on red lights blinking comes in exam, which can be solved in the same way
3. Reduce \begin{aligned}
\frac{803}{876}
\end{aligned} to the lowest terms.
- \begin{aligned} \frac{11}{12} \end{aligned}
- \begin{aligned} \frac{23}{24} \end{aligned}
- \begin{aligned} \frac{26}{27} \end{aligned}
- \begin{aligned} \frac{4}{7} \end{aligned}
Answer: Option A
Explanation:
HCF of 803 and 876 is 73, Divide both by 73, We get the answer 11/12
4. Find the greatest number which on dividing 1661 and 2045, leaves a reminder of 10 and 13 respectively
- 125
- 127
- 129
- 131
Answer: Option B
Explanation:
In this type of question, its obvious we need to calculate the HCF, trick is
HCF of (1661 - 10) and (2045 -13)
= HCF (1651, 2032) = 127
5. Find the LCM of \begin{aligned} \frac{2}{3}, \frac{4}{6}, \frac{8}{27} \end{aligned}
- \begin{aligned} \frac{2}{27} \end{aligned}
- \begin{aligned} \frac{8}{3} \end{aligned}
- \begin{aligned} \frac{2}{3} \end{aligned}
- \begin{aligned} \frac{8}{27} \end{aligned}
Answer: Option B
Explanation:
Whenever we have to solve this sort of question, remember the formula.
LCM = \\begin{aligned} \\frac{HCF of Denominators}{LCM of Numerators} \\end{aligned}
So answers will be option 2,
Please also give attention to the difference in formula of HCF and LCM