Question

The probability of selecting a blue marble at random from a jar that contains only blue black and green marble is 1/5 and the probability of selecting a black marble at random from the same Jagah is 1./4 if the jar contains 11 green Marbles find the total number of Marbles in the jar

Answer 1

Answer:

Step-by-step explanation:

it's Answer is 20

first let the green marbles be x

and the no. of marbles is n

Answer 2

Answer:

20

Step-by-step explanation:

Let the number of marbles are as given below

Number of blue marbles in the jar = a

Number of black marbles = b

Number of green marbles = c.

Given that probability of picking blue marbles at random = 1 / 5

a/(a + b + c) = 1 / 5

5a = a + b + c

4a = b + c

Given that 11 are green marbles.

4a = b + 11  ---------------------------E1

Probability of selcting black marbles = 1 / 4

b / (a + b + 11) = 1 / 4

3b = a + 11 ---------------------------E2

3*E1 + E2 gives us

12a + 3b = 3b + 33 + a + 11

11a = 44

a = 4, b = 5.  

Total number of marbles in the jar = 4 + 5 + 11 = 20