Year 12s: what will be the first way you research your future options? >>

Year 12s: what will be the first way you research your future options? >>

Year 12s: what will be the first way you research your future options? >>

Statistics Probability Question

Four letters are picked at random from the word THURSDAY. What is theprobability that there is at least one vowel among the letters?

(a)¹¹/₁₄(b)⁴/₇(c)³/₁₄(d)¹/₁₅

I'm just a bit confused about what to do.
I know the total number of possibilities is ⁸C₄=70 but I don't know where to go from there.
Help is appreciated, thanks in advance :smile:

:smile:

Original post by jamesthelam

Four letters are picked at random from the word THURSDAY. What is theprobability that there is at least one vowel among the letters?

(a)¹¹/₁₄(b)⁴/₇(c)³/₁₄(d)¹/₁₅

I'm just a bit confused about what to do.
I know the total number of possibilities is ⁸C₄=70 but I don't know where to go from there.
Help is appreciated, thanks in advance :smile:

:smile:

Let

v

be the number of vowels picked.

\mathbb{P}(v \geq 1) = 1- \mathbb{P}(v=0)

.
Now consider the ways one can pick no vowels at all.

OP

Original post by joostan

Let

v

be the number of vowels picked.

\mathbb{P}(v \geq 1) = 1- \mathbb{P}(v=0)

.
Now consider the ways one can pick no vowels at all.

Thanks, now that I think about it, it's obvious :biggrin:

:biggrin:

Original post by jamesthelam

Thanks, now that I think about it, it's obvious :biggrin:

:biggrin:

It crops up fairly frequently -something to watch out for.

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