In my opinion, the chance that a player is exactly back where they started is 1/16. Regarding the direction, after his first move, he has a 1/4 chance to go to the opposite direction (for example, if his first move is to right, he has a 1/4 chance to move to left at the second move). With respect to the number of steps, the situation is the same: he has a 1/4 chance to hit the same number of steps after the first on move on the steps counter, therefore the chance to be back exactly where he started from is 1/4 * 1/4 = 1/16, but the answer is 1/8.
A children's game is played on a square grid starting in the centre. Players spin two spinners to decide how to move their counters. The first spinner decides the direction (Left, Right, Up or Down) and the second spinner decides the distance (1, 2, 3 or 4 squares).
What are the chances that, after two moves, a player is exactly back where they started?
I got 1/16 as well, my method is probably bad though.
I did 0.25^4, which is the probably of any one combination that will get you back to where you start. eg, L 1 R 1 (as each spin is 0.25). Then I multiplied by 16, as I thought there were 16 ways of it happening. However, I suspect you are meant to multiply by 32, if the answer is 1/8.
Been too long since I've done probability...
EDIT: Lol, yeah, as below, the markscheme says 1/16..........
I got the half life to be 2.76 as half of 220 is 110 which corresponds to slightly more than 2.5. The fact that the radiation reaches the detector at 30cm with high energy but not at 100cm makes me think beta, as alpha wouldn't reach the first detector and gamma would reach both with fairly high energy.
I got the half life to be 2.76 as half of 220 is 110 which corresponds to slightly more than 2.5. The fact that the radiation reaches the detector at 30cm with high energy but not at 100cm makes me think beta, as alpha wouldn't reach the first detector and gamma would reach both with fairly high energy.
Can anyone confirm or refute?
The radiation is beta, but you have the wrong half life.
First calculate the average speed for the first 48 m which is 4 m/s. Then calculate the average speed from the last 84 m which seems 7 m/s. Then calculate the the acceleration which is (7 - 4)/12 => notice that there are 3 equal spaces and the answer is 0.25 which is D is think.