SOLUTION: The experimental probability of a penny landing on tails is 9/16. If the penny landed on heads 21 times, how many times was the coin tossed?

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Question 1025757: The experimental probability of a penny landing on tails is 9/16. If the penny landed on heads 21 times, how many times was the coin tossed?
Found 2 solutions by stanbon, Theo:
Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website!
The experimental probability of a penny landing on tails is 9/16. If the penny landed on heads 21 times, how many times was the coin tossed?
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P(heads) = 7/16 = 21/48
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Ans: 48 times
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Cheers,
Stan H.
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Answer by Theo(13342) (Show Source):
You can put this solution on YOUR website!
probability of tails is 9/16.

therefore the probability of heads is 7/16.

the penny lands on heads 21 times.

let x = the number of tosses.

you get 7/16 * x = 21

multiply both sides of this eqution by 16/7 to get x = 21 * 16/7

since 21/7 = 3, you get x = 3 * 16 which is equal to 48.

the number of tosses is 48.

21 of those tosses equals heads.

this means that 27 of those tosses equals tails.

the probability of tails is therefore 27/48.

divide numerator and denominator by 3 and you get 9/16.

that's the probability of getting tails, so the solution is good.

the number of tosses has to be 48.

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