Please help me with this maths problem :?

Question

20 passengers are in a sinking ship. Ten are mathematicians. They all stand in a ring. Every 7th passenger climbs into the life boat which can hold 10 people. At what position should the mathematicians be standing in the ring so as to board the life boat?

Answer 1

I agree totally with Pierre. He has the right idea. Once a mathematician leaves, he takes himself out of the circle, so the way the next guy to leave is seen changes. Way to go, Pierre. I gave you a thumbs - up!

Answer 2

Some of these answer are incorrect. Remember that every 7th person you pick climbs INTO the boat and takes himself out of the circle. After you go around the original 20, you only have 18 left. So it is not good enough to just mark every 7th one in a circle. You have to take them out. Number 20 tokens and remove each 7th one chosen excluding them from the count as you count every 7th place in the circle.

So you'll get the first two which are #7 and #14 all right, but then there's a reduced set. The next picked is 21, but since you've gone around the 20 it's really #1.

(1) 2 3 4 5 6 8 9 10 11 12 13 15 16 17 18 19 20

The next picks are #9 and #17 from the original circle, count 3 to #20 and four more to pick #5. But by then your circle is further reduced:

2 3 4 (5) 6 8 10 11 12 13 15 16 18 19 20

The next picks round the circle are #15 and #4, by then the circle is

2 3 (4) 6 8 10 11 12 13 16 18 19 20

Next picks are #16 and #8, at which point you have

2 3 6 10 11 12 13 18 19 20

These are the hapless people who will go down with the ship, and the people you picked, in the original circle, were these numbers:

1 4 5 7 8 9 14 15 16 17 (answer)

Answer 3

Assuming the first person to get into the boat will be in position 7, the positions you want are 1, 2, 3, 7, 8, 9, 10, 14, 15, and 16. I just drew a circle with 20 numbered positions, then went around it, marking every 7th spot with an "M".

Answer 4

try numbers:
7, 14, 1, 8, 15, 2, 9, 16, 3, 10
The first person to go in would be number 7 then seven numbers from that one would be 14, then 21 or as in this case 1, then seven more from that would be 8, then so forth until you have all 10 in the life boat.
I hope you get this right.
Good Luck ;)
After answering, I noticed that other people had the same numbers. Put them in the order that they would be counted, nut in numerical order. Like 1-6 7th peson jump in, and so forth. Like I wrote it down. Some teachers are anal about that kind thing. You may have the correct numbers, but in the correct order.

Answer 5

well i guess de following positions order:
1,2,3,7,8,9,10,14,15,16

hope so dat its de right answer.

Answer 6

1st
4th
5th
7th
8th
9th
14th
15th
16th
17th
I think... lol