Friday

September 19, 2014

September 19, 2014

Posted by **pooja** on Saturday, March 17, 2012 at 10:32am.

Some of the sections are shaded.

Each time the spinner is spun it stops on one of the six sections.

It is equally likely that it stops on any one of the sections.

(a)The spinner is now spun twice. find the probability that the total of the 2 numbers is

(i)20 (ii) 11

(b)The spinner is now spun until it stops on a section numbered 2.

The probability that this happens on the nth spin is

16/243.

Find the value of n.

kindly show the steps

- maths-probability -
**Reiny**, Saturday, March 17, 2012 at 1:34pmSince all you can get is 1, 2 or 6

there is no way to get a total of 20 or 11 with only 2 spins.

looks like either a typo or a flaw in the question.

2nd part.

Spin until you get a 2 ....

getting a 2 on

1 spin = (1/3)

2 spins = (2/3)(1/3) = 2^1 / 3^2

3 spins = (2/3)^2 (1/3) = 2^2 / 3^3

4 spins = (2/3)^3 (1/3) = 2^3 / 3^4

...

n spins = 2^(n-1) / 3^n

so 2^(n-1) / 3^n = 16/243

2^(n-1) / 3^n = 2^4 / 3^5

n = 5

**Answer this Question**

**Related Questions**

Math - You roll a number cube numbered from 1 to 6. You then spin a spinner with...

Probability - What is the probability of spinning a number greater than 5 OR ...

math - A spinner is divided into 5 equal sections numbered 1, 2, 3, 4, and 5. If...

Math. - A spinner is divided into 8 equal sections. There are 3 yellow sections ...

Math - My question: A spinner looks like this: A disc divided into sections that...

Math (check) - 4. A spinner is divided into 10 equal sections numbered from 1 to...

math (cant figure it out) - 4. A spinner is divided into 10 equal sections ...

MATH - A spinner is divided into 10 equal sections numbered from 0 to 10. You ...

Probability - The spinner has 6 sections 2 of which are 2. The spinner is now ...

Math - I am stuck on several probability questions. A spinner that has 15 equal ...