Question

A jar contains 2 pennies, 7 nickels and 3 dimes. A child selects 2 coins at random without replacement from the jar. Let X represent the amount in cents of the selected coins.

(a) Find P(x=10)

(b) Find P(x=11)

(c) Find the expected value of X

Answer 1

Qiven Jar & fennies 2 pennies Cf nickes C Comtains, nickels = 7 -3 Dimes (D t dimes 2 Coins that, Knous we 10 2 N 10 P- 10 Ceris C oittou elacement, child Selects 2 00ins ar andm be the amounr Cents PCX1) USing 2 Coins makiny 1a Cents 2 NTCKEIS xIO means Selechiny g Nickels Cuithoui Dedacement 7C6 PCx 12Ci) 12c1 Cents. USIny 2 Coins = makiny dime and 1 Penny. means Setectinr L D+L P wirhout replaemen 3CI 2c 2(3 3C2) 12CII) Exxpected valye X. 2 COins Can Select we Out d 2 p, 7 N, 3 D m them is

PCK2) 2P Pti P 2Nニ1N+」 PCx20) 20 こ1D+ 1D ニPCX=5) NLD PCx 2 c 12Ci) 2.C 2 (2)t23 12 C1) 2c 20。ギてc 44 12c 12 C1) 24 3 c 7e, 3C + 1c PCx5) 12C 1201) 12C 3(2) 2i PCx26) 21 12C11 6 2. 42 2 12 132 32 13 2 13 2 13 2 13 2 ECx)x P(x) C ) ('474) 28 2 132 . 17 3 2