a box contains red colour and black colour marble. the total number is 50. if 10 black colour marble are added and mixed the probability of drawing a red colour marble is a 7/12 what was the original number of black marbles?
Answers
Answer: 15
Step-by-step explanation:
Probability of drawing a red coloured marble is 7/12,
Dividing and multiplying the probability by 5, we get ,
(7/12)*(5/5)= 35/60
Therefore ,
Probability of drawing a black marble is 25/60
Therefore, there are 25 black coloured marbles
The original number of black marbles = 25-10= 15 black coloured marbles
Answer:
15 black marble
Step-by-step explanation:
let there be X number of red marble initially so number of black marbles initially becomes 50 - x and further 10 black marbles added so the total number of marbles become 60 but the number of red marbles remains same as X but the total number of black marbles become 60 - x and from the question probability of drawing right marble is 7 by 12 and from the condition from the question X/60 is equal to 7/12 which gives the number of red marbles as 35 and subtracting this from 50 gives the number of black marble initially as 15
