Pls Help... Answer needed urgently!?

Question

Three night guards A, B and C blow their whistles at intervals of 8, 15 and 18 minutes respectively. If they blow it together at 11pm when next are they expected to blow together. Show workings

Answer 1

They blow their whistle at intervals of 8,15 and 18 minutes
Hence the minimum time-interval after which these will be blown together is the LCM of 8,15 and 18 minutes
LCM of 8,15 and 18
=360
Therefore the whistles will again be blown together after 360 minutes or 6 hours that is at 5 am

Answer 2

Start with Guards A and B. They will blow their whistle together every 120 minutes (8*15). Guard C will match at 360 minutes. (18*20). So at 5 AM is the answer

Answer 3

The question is basically asking for the "least common multiple" of 8, 15, and 18. This is because we want to know a time when the number of minutes it has been since 11pm is a multiple of 8, 15 and 18 minutes because if that is the case then all three will blow thier wistles. It also needs to be the first time this happens after 11pm.

One way to do this is to realize that a number can be written as a product of prime numbers in a unique way. Call the # of minutes after 11pm that they all blow their wistles N. We want N to be a multple of 8, which is 2^3, so N has a 2 in its factorization that is at least cubed. N also needs to be a multiple of 15, which is 3*5, so N also has at least one factor of 3 and 5. Finally, N needs to be a multiple of 18, which is 3^2 * 2, so N has a three that is at least squared and at least one factor of two.

Combining all of these requiremnets, 2 has to be at least cubed, 3 has to be at least squared, and there is at least one factor of 5. No other factor is needed. So, the smallest number satisfying all of these requirements is
2^3 * 3^2 * 5 = 360 minutes = 6 hours
6 hours after 11pm is 5am.

Answer 4

You need the LCM of 8,15 and 18.
Let's do the LCM 2 numbers at a time.
1). Since 8 and 15 have no factor in common,
their LCM is 8*15 = 120.
2. In general LCM of a and b = ab/ gcd(a,b)
So the LCM of 120 and 18 = 120*18/6 = 120*3 = 360.
So the next time they will blow together is 6 hours
later or 5 am.

Answer 5

Basically it's a question asking you for lowest common multiple of 8, 15 and 18.

Convert the three numbers into the product of their prime numbers:
8=2*2*2
15=3*5
18=2*3*3
LCM=2*2*2*3*3*5 = 360

360 min ie 6hrs after 11pm is 5am.

When in doubt, simply draw a table and slowly work through down until you see all three columns have the same (lowest) number. Ie,
A B C
8 15 18
16 30 36
24 45 54
32 60 72
etc. although this can take a while.

Answer 6

5:00 am, NOT 5:30 am!

You need the LCM of 8, 15 and 18 minutes.

8 = 2^3, 15 = 3*5, and 18 = 2*3^2, so that the LCM must be

2^3*3^2*5 = 8*9*5 = 8*45 mins = 8*3/4 hrs = 6 hrs; and 6 hrs after 11 pm is at 5:00 am.

Live long and prosper.

Answer 7

360/8=45
360/15=24
360/18=20 Therefore at 360 min. or 6 hours later they will blow whistles. At 5 pm the trifecta will take place!

Answer 8

Crying often does not mean that you are spoiled, selfish or a baby; it may just be how you need to express yourself and your emotions right now. If you start to feel that your emotions are totally out of control, it may be a very good idea to speak with someone like a counselor or an adult you trust. But I firmly believe that everyone has their own unique way of expressing their emotions. Crying doesn't hurt anyone and it is a useful way to express yourself. It's much better than bottling up emotions that may come out in a more destructive way. I was and am a pretty big crier so I am not sure if I am being totally impartial, but I am pretty sure that I am.

Answer 9

5:30am