Monday

March 2, 2015

March 2, 2015

Posted by **Shelagh** on Wednesday, June 18, 2014 at 7:30pm.

(a) exactly three coins land heads up

(b) all coins land tails up

(c) two or more coins land heads up

(d) no more than two coins land tails up

(e) at least one coin lands tails up

- Math -
**MathMate**, Thursday, June 19, 2014 at 6:27amEach coin can land heads or tails with equal probability of 1/2.

Dropping a coin four times has 2^4=16 possible outcomes.

(a) three heads

By enumeration:

There are four possible outcomes, so the probability is 4/16. THHH,HTHH,HHTH,HHHT.

The number of combinations for 3H can be calculated as 4C3=4!/((1!)(3!))

So probability = 4C3/16

If you are familiar with the binomial probability formula, then

P(3H)=4C3*(1/2)^3(1/2)^1

=4!/(1!3!)*(1/16)=4/16

(b) there can be only one outcome out of 16.

(c)Use enumeration, or combination to find 4C2+4C3+4C4

(d)(e) similar to above.

**Answer this Question**

**Related Questions**

Math - A game is played flipping three coins. If all three coins land heads up ...

Word Problem. - A game is played by flipping three coins. If all three coins ...

math - you have16 coins that are heads up an18 coins that are tails up. After ...

Math (please help!) - You have 16 coins that are heads up and 18 coins that are ...

Math - You have 16 coins that are heads up and 18 coins that are tails up. After...

Math - You have 16 coins that are heads up and 18 coins that are tails up. After...

math - two coins are tossed list all the possible outcomes what is the ...

math - A game is played by flipping three coins. If all three coins lands heads ...

Math: Probablity - A penny, a nickel, and a dime are flipped at the same time. ...

probability - you have 16 coins that are heads up and 18 coins that are tails up...