Probability/Statistics
posted by Jon on .
1)Two marbles are chosen at random from a bag containing 3 blue and 2 red marbles. The relativefrequency histogram shows the distribution of the number of red marbles chosen. Find P(0 red). (the gragh shows 3/10 for 0 red, 3/5 for 1 red, and 1/10 for 2 red)
A)0
B)8/15
C)3/10
D)2/5
I chose C
2)A red die and a blue die are tossed. What is the probability that the red die shows a 3 and the blue die shows a number greater than 3?
A)1/10
B)1/5
C)1/12
D)3/5
I chose C
3)Tickets are numbered 1 to 50 and placed in a box. Three tickets are drawn at random without replacement. What is the probability that their numbers are all greater than 25?
A)1/8
B)23/196
C)69/625
D)1/2
I chose D
4)From 4 yellow and 8 blue marbles, 3 are selected. What is the probability that all 3 are yellow or all 3 are blue.
A)3/11
B)1/55
C)14/55
D)3/220
I don't know I GUESS A
5)A card is drawn from a standard deck of cards. What is P(heart or a 6)?
A)9/26
B)17/52
C)1/4
D)4/13
I chose B

5) There are 13 hearts and 3 sixes that are not hearts. You can't count the six of hearts twice. That makes 16/52. Which fraction choice is that?

1 and 2 are correct
for 3 I got 23/196
there are 25 tickets greater than 25
so prob = 25/50 x 24/49 x 23/48 = 23/196
for 4 you have to use a formula that says:
P(A or B) =P(A) + P(B)  P(A and B)
since the prob of them being 3 yellow AND 3 blue is zero
P(3yellow) = 4/12 x 3/11 x 2/10 = 1/55
P(3blue) = 8/12 x 7/11 x 6/10 = 14/55
so your prob = 1/55 + 14/55 = 3/11
GOOD GUESS
#5 (use the same formula as #4)
prob(heart) = 13/52
Prob(6) = 4/52
Prob(6of hearts) = 1/52
so prob(heart OR a 6) = 13/52 + 4/52  1/52
= 16/52
= 4/13