BrainDen.com - Brain Teasers
• 0

## Question

An oldie but quite interesting!!

Supposing a clock takes 7 sec to strike 7,how long will the same clock take to strike 10

## Recommended Posts

• 0

Assuming you start counting after the first strike, and that the strike itself takes no time, I would say 53 seconds

• 0

22 seconds

• 0
##### Share on other sites

• 0

First, Spoiler tag fail right there ^^

Second, most of my clocks don't ring.

##### Share on other sites

• 0

22 seconds

That's 22 seconds from the 7 seconds before it hits 7, from the time its at 7 it would be 15 seconds to get to the 10.

##### Share on other sites

• 0

autonav

Is this in the right section?

##### Share on other sites

• 0

it is talking about a clock, not a phone!

##### Share on other sites

• 0

Well that all depends on the clock, is the clock known to be slow or fast? If so how slow or fast? If it is known to be fast and it is now slow. Check the batteries. If it is normally slow and is now fast, you got something paranormal going on.

Edited by brandonyy4u
##### Share on other sites

• 0

[

quote name='autonav' date='15 February 2011 - 09:17 AM' timestamp='1297783022'

post='267637']

[spoiler='I think it's 10.5 seconds. It takes 7

seconds to ring 7 times. There are 6 intervals between rings. Each

interval then takes 7/6 of a second. For 10 rings, there are 9

intervals. So 9 x 7/6 = 63/6 = 10.5.'']

##### Share on other sites

• 0

it is talking about a clock, not a phone!

Don't understand this.

The OP asked how long does the clock take to STRIKE 10.

##### Share on other sites

• 0

Don't understand this.

The OP asked how long does the clock take to STRIKE 10.

right, not how long a phone takes to ring ten times, which seems to be what the post you were agreeing with is regarding

##### Share on other sites

• 0

right, not how long a phone takes to ring ten times, which seems to be what the post you were agreeing with is regarding

autonav might've chosen a better word than 'ring', but the question is 'How long does it take the clock to 'bong' 10 times?'

##### Share on other sites

• 0

autonav might've chosen a better word than 'ring', but the question is 'How long does it take the clock to 'bong' 10 times?'

I believe the question is "How long does it take a clock to strike 10?" Not 10 times...if that were the question, my Baconlicious Chum then there is missing info...how long does each "bong" take. No, the second hand has struck 7 (or will in 7 seconds). How long until it strikes 10.

##### Share on other sites

• 0

okay if thats the question then yes i agree with that, i was answering based on when the hand got to the numbers, and you're right autonav's wording confused the hell out of me

##### Share on other sites

• 0

My assumption is that the clock took 7 seconds to strike 7 - i.e. bong 7 times....as in

"It was a cold bright day in April and the clocks were striking 13."

edit -typo

Edited by fabpig
##### Share on other sites

• 0

My assumption is that the clock took 7 seconds to strike 7 - i.e. bong 7 times....as in

"It was a cold bright day in April and the clocks were striking 13."

edit -typo

I think it's 10.5 seconds. It takes 7 seconds to ring 7 times. There are 6 intervals between rings. Each interval then takes 7/6 of a second. For 10 rings, there are 9 intervals. So 9 x 7/6 = 63/6 = 10.5

But you can't answer that with the information given...as was noted one must calculate the intervals between strikes, but then one must know how long each strike takes. What if ezch strike took .1 second? then the interval lengths are (7-.7)/6 = 1.05 seconds between strikes...and the 10 strikes take 9.45 + .1 *10 = 10.45 seconds...see different answer...

.

##### Share on other sites

• 0

I think it's 10.5 seconds. It takes 7 seconds to ring 7 times. There are 6 intervals between rings. Each interval then takes 7/6 of a second. For 10 rings, there are 9 intervals. So 9 x 7/6 = 63/6 = 10.5

But you can't answer that with the information given...as was noted one must calculate the intervals between strikes, but then one must know how long each strike takes. What if ezch strike took .1 second? then the interval lengths are (7-.7)/6 = 1.05 seconds between strikes...and the 10 strikes take 9.45 + .1 *10 = 10.45 seconds...see different answer...

.

If this is how we're looking at it then autonav is correct, the strike length is irrelevant. The time of 7 seconds would be from when the first strike begins to the time the 7th strike begins, where each interval is the time from one strike beginning to the next strike beginning.

1st strike starts-2nd strike starts=1

2nd-3rd=2

3rd-4th=3

4th-5th=4

5th-6th=5

6th-7th=6

So there are 6 constant time intervals from the time the first strike begins to the time the 7th strike begins, therefore autonav's math is correct, each interval takes 7/6 seconds so the 9 intervals between the first strike and the beginning of the 10th strike would take 10.5 seconds. When the strike begins the strike begins, how long it lasts doesn't matter.

Edited by TheJMan211
##### Share on other sites

• 0

If this is how we're looking at it then autonav is correct, the strike length is irrelevant. The time of 7 seconds would be from when the first strike begins to the time the 7th strike begins, where each interval is the time from one strike beginning to the next strike beginning.

1st strike starts-2nd strike starts=1

2nd-3rd=2

3rd-4th=3

4th-5th=4

5th-6th=5

6th-7th=6

So there are 6 constant time intervals from the time the first strike begins to the time the 7th strike begins, therefore autonav's math is correct, each interval takes 7/6 seconds so the 9 intervals between the first strike and the beginning of the 10th strike would take 10.5 seconds. When the strike begins the strike begins, how long it lasts doesn't matter.

Thejman211 now you got it

YES ,Autonav you are absolutely correct

10.5 is correct.

##### Share on other sites

• 0

[spoiler=That seems to be the accepted answer. I'm still caught up on the semantics though. It seems that a strike hasn't occured until it completes, making the length of the strike very relevant. But once again, it seems it's just me and I'm caught up in the semantics. For the sake of the intention of the riddle then certainly I can agree with everyone (and Engineering.com ) that the answer is] 10.5

##### Share on other sites

• 0

How about 3 hours and 7 seconds? If it will be 7 seconds until it strikes 7, then 10 is three more hours away... Probably not the answer you're looking for, but that's my take!

## Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

×   Pasted as rich text.   Paste as plain text instead

Only 75 emoji are allowed.

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.