math
posted by shank .
a bag of marbles contains 5 red,7 green ,and some blue.if 1/3 of the marbles in the bag are blue,how many blue marbles are in the bag?

If there are only red, green and blue marbles in the bag, then given that 1/3 are blue, then red and green occupy 11/3=2/3 of the bag.
Use direct proportion:
2/3 bag : 5+7=12
1/3 bag : X
Cross multiply:
x=(1/3)*12÷(2/3)
=12/2
= 6 (blue marbles)
Respond to this Question
Similar Questions

math
a bag contains 33 green marbles and 25 blue marbles. you select a marble at random from the bag. find the theoretical probability of selecting a blue marble. thanks Pr(blue)= number blue/total marbles 
math
George has a bag of marbles. Inside the bag are 5 red marbles, 3 green marbles, and 2 blue marbles. He draws out two marbles in a row, without replacement. What is the number of outcomes? 
math
There are 25 red, blue, yellow and green marbles in a bag. Four of the marbles are blue and the probability of selecting a blue or green marble at random is 40%. Write and solve an equation to determine the number of green marbles … 
math
sally has a bag with red,blue, and green marbles. She has twice as many blue marbles as red marbles. She has 5 times as many green marbles as red marbles. Altogether she has 24 marbles. How many of each color marble does she have? 
math
A bag contains 5 red, 4 white and 6 blue marbles. Another bag with 9 blue marbles has the same ratio of blue to white marbles as the first bag. How many white marbles are there in the second bag? 
math
There are 5 red marbles, 6 blue marbles, e green marbles, and 2 yellow marbles in a bag. What percent or fraction represents the number of blue and green marbles in the bag? 
Math
A bag contains nine red marbles, four green marbles, three blue marbles, and two yellow marbles. If Lisa draws a random marble from the bag, what is the probability that it will be a red, green, or blue marble? 
Maths
Matt has a bag containing 12 green marbles and 8 blue marbles. Without looking, he pulls out one marbles and places it on the table. He then picks a second marbles from the bag. What is the probability he will have 2 blue marbles? 
Math HELP!!!!!
A bag contains 4 red marbles, 3 blue marbles, and 7 green marbles. If a marble is randomly selected from the bag, what is the probability that it is blue? 
Maths
A bag contains marbles of three different colours red, blue , yellow. 2/5 of the marbles are red. The ratio of the number of blue marbles to the number of yellow marbles is 5:7. What fraction of the marbles in the bag is blue?