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when a drawing pin is dropped onto the floor it lands either point up or point down the probability of any one drawing pin landing point up is 0.46

what is the probability that the first three drawing pins all land point down?

in the first case point down will be 0.54 as 0.46+0.54=1 is that right?

how do I find if at least one of the first three drawing pins dropped will land point up? do I do 0.54*0.54 = 0.2916 1-0.2916=0.7084 is that correct?

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    What do you know about probability? Have you studied what happens when you flip a fair coin? An unfair coin? – 2017-01-22
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    all I know is that probabilities add to 1 as opposed to the question I am asking – 2017-01-22

2 Answers 2

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Here is how to begin to think about the problem. I'll start it for two pins. You should be able to finish, and go on to work out the answer for three. (There is a formula for the answer, but I don't think memorizing it will be useful for you.)

up-up has probability $0.46 \times 0.46$ since the events are independent.

up-down has probability $0.46 \times 0.54$

down-up ...

down-down ...

When you're done you can check your work by seeing that the probabilities for the four possibilities add to $1$.

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    when it says find the probability that two of the first three drawing pins dropped land point down, does that mean 0.54*0.54? – 2017-01-22
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Yes all probabilities sum to 1.

P(Non Occurrence) = 1 - P(Occurrence)

P(Point down) = 1 - 0.46 = 0.54

Probability of 3 pins point down = 0.54 × 0.54 × 0.54