Hypothesis testing on either a Texas TI-83 plus or a Sharp EL-9900

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Hi, I'm sitting Edexcel S2 and I was wondering if anyone knew how to check hypothesis testing on either a Texas TI-83 plus or a Sharp EL-9900?

I think I need to select "Z-Test" and choose "Stats" on the first option that comes up, but I don't know what I should do from there.

An example of a hypothesis testing question I could get is:

A manufacturer of coloured drawing pins introduces a purple pin that is to make up 15% of the total production. The pins are sold in boxes of 20. A teacher buys a box of pins and discovers that it contains only 1 purple pin. Test, at the 5% significance level, whether or not there is evidence that the probability of a pin chosen at random being purple is less that 0.15.

So what I would do if I was working this out by hand is say:

X ~ B(20,p)

H_0: p=0.15

H_1: p<0.15

\alpha = 0.05

Reject H_0 if:

P(X \leq 1| p = 0.15) \leq 0.05

P(X \leq 1| p = 0.15) = 0.1756

0.1756 > 0.05

Therefore insufficient evidence to reject H_0

Does anyone know how to check this on a calculator?

Thank you!
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VannR
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As far as I know (using a Casio fx-991ES PLUS, but the features are pretty similar), you cannot check cumulative binomial probabilities using a scientific calculator. The z-test option is for calculation cumulative probabilities of the standard normal variable Z, not binomially distributed variables.
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The best way of checking your answer is to use binomial tables, failing that, calculate the sum of the probability of the random variable having every value defined in the range and taking its sum, but this takes far too long to consider doing in an exam. Just stick with the tables.
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(Original post by VannR)
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Ahh, okay. That makes sense. Thank you!
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