BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Fair and Biased Coin

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Master | Next Rank: 500 Posts
Posts: 487
Joined: Fri Mar 27, 2009 5:49 am
Thanked: 36 times

Fair and Biased Coin

by dtweah » Sun Mar 07, 2010 1:08 pm
A box contains 4 fair coins and 6 biased coins. Whenever a fair coin is
fipped, it comes up heads with probability 0:5. Whenever a biased coin
is ipped, it comes up heads with probability 0:8. A coin is randomly
chosen from the box and then ipped. What is the probability that it
will come up heads?

(a) 0:6
(b) 0:64
(c) 0:68
d) 0:72
(e) 0:76
Top
Source: — Problem Solving |
User avatar
Master | Next Rank: 500 Posts
Posts: 102
Joined: Sat Feb 20, 2010 5:38 am
Location: IIM Ahmedabad
Thanked: 10 times

by firdaus117 » Sun Mar 07, 2010 9:40 pm
probability that it will come up heads=(Probability of selecting a fair coin X Probability of getting head on a fair coin)+(Probability of selecting a biased coin X Probability of getting head on a biased coin)
[spoiler] =0.4*0.5+0.6*0.8
=0.2+0.48
=0.68 Option C[/spoiler]
Top
Post new topic Post Reply
• Page 1 of 1