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SAT math probability

How can we find the answer to the following SAT math question:

"Four fair coins are tossed. Find the probability that all of them will come up tails ?"

Thanks!

miranda

08-18-2013, 01:16 PM

"Four fair coins are tossed. Find the probability that all of them will come up tails ?"

The probability thatall of them will come up tails means:

TTTT

There is only one way to get four tails - the first toss is tails, the second is tails, the third is tails and the fourth is tails.

Due to the multplication principle (When two or more compound independent events occur, we use multiplication to determine their probability. To find the probability that first event happens and second event happens, we should multiply the probability that the first event happens times the probability that the second event happens. ) we have that the probability of TTTT occurring is

P(all \ coins \ will \ come \ up \ tails )=\frac{1}{2 }\cdot \frac{1}{2 }\cdot \frac{1}{2 }\cdot \frac{1}{2 }=\frac{1}{2^4 }=\frac{1}{16}

Hope these help!!

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