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Six bells commence tolling together and toll at the intervals of 2,4,6,8,10,12 seconds resp. In 60 minutes how many times they will toll together.

  • 15
  • 16
  • 30
  • 31

Answer: Option D

Explanation:

LCM of 2-4-6-8-10-12 is 120 seconds, that is 2 minutes.

Now 60/2 = 30
Adding one bell at the starting it will 30+1 = 31

Similar Questions :

1. Find the HCF of
\begin{aligned}
2^2 \times 3^2 \times 7^2, 2 \times 3^4 \times 7
\end{aligned}

  • 128
  • 126
  • 146
  • 434

Answer: Option B

Explanation:

HCF is Highest common factor, so we need to get the common highest factors among given values. So we got
2 * 3*3 * 7

2. 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

3. Find the largest number of four digits which is exactly divisible by 27,18,12,15

  • 9700
  • 9710
  • 9720
  • 9730

Answer: Option C

Explanation:

LCM of 27-18-12-15 is 540.
After dividing 9999 by 540 we get 279 remainder.
So answer will be 9999-279 = 9720

4. The H.C.F. and L.C.M. of two numbers are 12 and 5040 respectively If one of the numbers is 144, find the other number

  • 400
  • 256
  • 120
  • 420

Answer: Option D

Explanation:

Solve this question by using below formula.
Product of 2 numbers = product of their HCF and LCM

144 * x = 12 * 5040

x = (12*5040)/144 = 420

5. Reduce \begin{aligned}
\frac{368}{575}
\end{aligned} to the lowest terms.

  • \begin{aligned} \frac{30}{25} \end{aligned}
  • \begin{aligned} \frac{28}{29} \end{aligned}
  • \begin{aligned} \frac{28}{29} \end{aligned}
  • \begin{aligned} \frac{16}{25} \end{aligned}

Answer: Option D

Explanation:

We can do it easily by in two steps
Step1: We get the HCF of 368 and 575 which is 23
Step2: Divide both by 23, we will get the answer 16/25

Read more from - HCF and LCM Questions Answers
Post a comment

  • Roshan J 8 years ago

    hi mastguru could you please explain this answer:
    1. why LCM is followed?
    2. And why +1 is done at the end?

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