Maths help.

The probability of spinning a 1 on a spinner twice in a row is 1/36. Work out the angle of the sector labelled 1. (3)

I haven't been given the radius of the spinner so I can't work out the arc length or sector area and rearrange that to get the angle.
I also thought it would be 10/360 if I multiply the top and bottom of the fraction by 10 and so the angle would be 10 degrees but that seems too simple.

Reply 1

Guertena Weiss

6

square root of 1/36 is 1/6 which gives you the probability of spinning a 1 (once), 360x(1/6) = 60

Reply 2

F3rnw3h

13

If the probability of spinning a 1 twice is 1/36, then the probability of spinning a 1 is 1/6 (1/6 x 1/6 = 1/36) So assuming the probability of each number is equal, there are 6 numbers on the spinner, and assuming each number takes up the same area, the angle will be 1/6 of 360° Hope that helps!

Original post by Maths1210

The probability of spinning a 1 on a spinner twice in a row is 1/36. Work out the angle of the sector labelled 1. (3)

I haven't been given the radius of the spinner so I can't work out the arc length or sector area and rearrange that to get the angle.
I also thought it would be 10/360 if I multiply the top and bottom of the fraction by 10 and so the angle would be 10 degrees but that seems too simple.

A spinner is in a shape of a circle, and there are 360 degrees in a circle. There are a certain amount of equal sectors with different digits on them, and they equally divide these 360 degrees.

We are told that a spinner is spun twice and the probability of getting the same value is 1/36. Clearly, when two events happen, we multiply their probabilities together. So here event is 'getting a 1' and if it happens twice we just multiply its probability by itself. If we say that it happens with probability

p

, then we have

p^2=\frac{1}{36}

and thus we can determine what the probability is

p

. This probability also tells us about the amount of sections that our circle is divided into, hence by how much we need to divide 360 by for our sector's area.