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# Question about One and two tailed tests watch

1. Shell wants to test whether a coin is biased. She tosses the coin 100 times and counts the number of times she gets a head. Shell says the test statistic is the probability of the coin landing on heads.

a) Explain the mistake that Shell has made and state the correct test statistic.

I got this part correct.

b) State the null hypothesis.

Also got this correct.

c)State the alternate hypothesis.

What makes this a two-tailed test? I initially put H1, p>0.5.
2. (Original post by dont know it)
Shell wants to test whether a coin is biased. She tosses the coin 100 times and counts the number of times she gets a head. Shell says the test statistic is the probability of the coin landing on heads.

a) Explain the mistake that Shell has made and state the correct test statistic.

I got this part correct.

b) State the null hypothesis.

Also got this correct.

c)State the alternate hypothesis.

What makes this a two-tailed test? I initially put H1, p>0.5.
At the beginning it says she wants to test whether the coin is biased. The coin can be biased for heads or for tails so you have to look at a two tailed test. If you just say H1 : p>0.5 I think you are testing only whether its bias in favour of heads. So H1 : p=/= 0.5 I think is the way to go.
3. (Original post by dont know it)
Shell wants to test whether a coin is biased. She tosses the coin 100 times and counts the number of times she gets a head. Shell says the test statistic is the probability of the coin landing on heads.

a) Explain the mistake that Shell has made and state the correct test statistic.

I got this part correct.

b) State the null hypothesis.

Also got this correct.

c)State the alternate hypothesis.

What makes this a two-tailed test? I initially put H1, p>0.5.
This is a two-tailed test (rather ironically since the coin itself only has one tail). She isn't asking "Does this coin come up on heads more often" - she's asking "Is the coin biased". That can go either way, so your alternate hypothesis is p=/=0.5.

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