Question

A ball is drawn from a box containing 5 red, 8 black and 7 blue balls. Determine the probability that:
a) if a ball is drawn at random, it is black.
answer i got: 0.40
b) if two balls are drawn, they are both black. answer i got: 0.1474
c) if three balls are drawn, exactly one is black, one is blue and one is red.
d) if three balls are drawn, at least one is black. e) if four balls are drawn, at most one of them is black.
Note: All selection is without replacement.

can you please check the answers i got is right or wrong and can you help me solve c, d, and e too.

Answer 1

a and b are correct

Answer 2

great :)
could you help me solve the other ones as well. i'm keep getting wrong answers i think i'm doing something wrong. no idea

Answer 3

c)
total balls= 20
8/20 * 7/19 * 5/18 = 0.0409

Answer 4

i got had got the same answer for c

Answer 5

so is it wrong??

Answer 6

i wasn't sure if i did it right or wrong
i wanted to make sure i did it right, since you got the same answer it should be correct

Answer 7

d) 8/20 * 7/19 * 6/18

Answer 8

can you please explain it to me how you got that

Answer 9

i got that 8/20 is for black ball

Answer 10

total = 20
black = 8
first event to choose any black from 20 balls = 8/20
second event the same , but now we have only 19 balls remaining so 7/19
third event , now only 18 balls remaining and also 6 black remaining so 6/18.

Answer 11

but over here we choosing 3 black balls

Answer 12

does it means 1 black and 2 random. actually that's the part that i didn;t get

Answer 13

@BangkokGarrett will help ya... he's good in explaining probabilities.

Answer 14

thanks and what would be the answer for e

Answer 15

could you please show me the answer for that E as well please

Answer 16

0.154 i guess

Answer 17

8/20 * 12/19 * 11/18
12 = all balls except black ones

Answer 18

maybe its right i'm not sure

Answer 19

i 'll tell u tommorrow, ok?

Answer 20

ok
can you please check a answer me for a question?

Answer 21

A process is thought to output an overall rate of 4% nonconforming parts. In a random sample of 50 such parts, what is the probability of 2 nonconforming parts?
Solve the problem to four significant digits, in two ways-using the binomial distribution and the Poisson approximation to the binomial distribution.

for this question i used binomial distribution ans i got the answer 0.2762

Answer 22

and for this question do i have to solve it by both methods?

Answer 23

that's not of my level.. sorry can't help with this one.

Answer 24

ok no problem.
could you help me with this question

Determine the probability of the following:
a) An odd number appears in a single toss of a fair die. Answer i got: 0.5
b) At least one tail appears in two tosses of a coin. Answer i got: 1/4 = 0.25
c) The sum 7 appears in a single toss of a pair of fair die. need help with this one

Answer 25

total outcomes 6^2 = 36
Now we have to calculate the numbers that make 7.
for example: 1+6 =7
2+5 = 7
3+4=7
and there opposite 6+!, 5+2, 4+3
total = 6
P = 6 / 36 = 1/6
yer ans??

Answer 26

ohhh i got it thanks

Answer 27

yea

Answer 28

thanks

In a country club, 80% of women play tennis, 20% play pool and 10% play both tennis and pool. If a woman is chosen at random, find the probability:
a) that she plays tennis or pool.
b) that she plays neither tennis or pool.
c) if she plays tennis what is the probability she plays pool?
d) if she plays pool what is the probability she play tennis?

Answer 29

a) answer is 90%
b) answer is 10%
c) 10%/80% = 1/8
d) 10%/20% = 0.5

Answer 30

these are the answers that i got

Answer 31

c and d are correct... dunno bout a and b

Answer 32

thank you so much for helping today, i really appreciate it. :)

Answer 33

yw..

Answer 34

@ganeshie8

Answer 35

@ganeshie8 can u explain me part D?

Answer 36

In a country club, 80% of women play tennis, 20% play pool and 10% play both tennis and pool. If a woman is chosen at random, find the probability:
a) that she plays tennis or pool.
b) that she plays neither tennis or pool.
c) if she plays tennis what is the probability she plays pool?
d) if she plays pool what is the probability she play tennis?

Answer 37

is this the question ?

Answer 38

no,, question related to balls.

Answer 39

A ball is drawn from a box containing 5 red, 8 black and 7 blue balls. Determine the probability that:
a) if a ball is drawn at random, it is black.
answer i got: 0.40
b) if two balls are drawn, they are both black. answer i got: 0.1474
c) if three balls are drawn, exactly one is black, one is blue and one is red.
d) if three balls are drawn, at least one is black. e) if four balls are drawn, at most one of them is black.
Note: All selection is without replacement.

can you please check the answers i got is right or wrong and can you help me solve c, d, and e too.

Answer 40

this one

Answer 41

d) if three balls are drawn, at least one is black.

Answer 42

probability for having "at least one black" = 1 - probability for having NONE of them black

Answer 43

P for NONE black = 12/20 * 11/19 ??? right??

Answer 44

yes, since it is without replacement, P for NONE of them black = 12/20*11/19*10/18

Answer 45

simply subtract it from 1, u wud get the probability for complement event : "atleast one of them black"

Answer 46

11/57 ??

Answer 47

11/57 is for NONE of them black

Answer 48

1 - 11/57 = 46/57

Answer 49

yess

Answer 50

thanks... now part E. plz

Answer 51

part E for exact one black ball

Answer 52

e) if four balls are drawn, at most one of them is black.

Answer 53

P for "atmost one of them black" = P for "NONE of them black" + P for "ONE of them black"

Answer 54

we have calculated NONE, 11/57

Answer 55

no

Answer 56

that was for three balls

Answer 57

yahh we need to calculate again

Answer 58

12/20 * 11/19 * 10/18 * 9/17 = 11/ 57 * 9/17 = 33/323 right??

Answer 59

correct !

Answer 60

P for one black = 8/20 ???

Answer 61

try again

Answer 62

8/20 * 7/19 * 6/18 * 5/17 ?????

Answer 63

nope

Answer 64

remember you want "P for EXACTLY one of them black"

Answer 65

since you're drawing FOUR balls,
first can be BLACK, and remaining needs to be other colors

Answer 66

second can be BLACK, and remaining needs to be other colors

Answer 67

third can be BLACK, and remaining needs to be other colors

Answer 68

fourth can be BLACK, and remaining needs to be other colors

Answer 69

12/20 * 11/19 * 10/18 * 8/17???

Answer 70

nope, u need to consider FOUR cases and add all the probabilities

Answer 71

P(EXACTLY one ball black) = P(first ball black, all others not black) + P(second ball black, all others not black) + P(third ball black, all others not black) + P(fourth ball black, all others not black)

Answer 72

getting ?

Answer 73

four cases for getting exactly one black :-

1) \(BLACK, OTHER, OTHER, OTHER\)

2) \(OTHER, BLACK, OTHER, OTHER\)

3) \(OTHER, OTHER, BLACK, OTHER\)

4) \(OTHER, OTHER, OTHER, BLACK\)

Answer 74

when u work each case and add the probabilities u would get :-

P(exactly one black ball) =

\(\large \frac{8}{20}*\frac{12}{19} * \frac{11}{18} *\frac{10}{17} + \\ \frac{12}{20}*\frac{8}{19} * \frac{11}{18} *\frac{10}{17} + \\ \frac{12}{20}*\frac{11}{19} * \frac{8}{18} *\frac{10}{17} + \\ \frac{12}{20}*\frac{11}{19} * \frac{10}{18} *\frac{8}{17} \\ = \frac{352}{969} \)

Answer 75

@ganeshie8 got it... thanks!!