Red balls

In the bag there are 3 red, 12 blue and 8 green balls. How many red balls we must be attached to the bag if we want the probability of pulling out the red balls was 20%?

Correct result:

n =  2

Solution:

(n+3) / (3+12+8+n) = 20/100

(3+12+8+n) • ( (n+3) / (3+12+8+n) ) = (3+12+8+n) • ( 20/100 )

80n = 160

n = 2

Calculated by our simple equation calculator.

Try another example

Please write to us with your comment on the math problem or ask something. Thank you for helping each other - students, teachers, parents, and problem authors.

Showing 0 comments:

Next similar math problems:

• There
  There are 32 trees of three species in the orchard. 25% cherries, three eighty pears, others plums. How many plums are in the orchard?
• Holidays - on pool
  Children's tickets to the swimming pool stands x € for an adult is € 2 more expensive. There was m children in the swimming pool and adults three times less. How many euros make treasurer for pool entry?
• Company and employees
  There are 370 employees in the company - women are 15% less than men. How many men work in the company?
• Today in school
  There are 9 girls and 11 boys in the class today. What is the probability that Suzan will go to the board today?
• Salary in enterprise
  The average salary in the company is 27 000 CZK, 30% of workers have the lowest average income of 19 thousand CZK. There were an increase in the salary in this group by 2%. How much % increased the average salary across the company?
• Researchers
  Researchers ask 200 families whether or not they were the homeowner and how many cars they had. Their response was homeowner: 14 no car or one car, two or more cars 86, not homeowner: 38 no car or one car, two or more cars 62. What percent of the families
• Summerjob
  The temporary workers planted new trees. Of the total number of 500 seedlings, they managed to plant 426. How many percents did they meet the daily planting limit?
• Merchant
  The merchant lower cost by 10% in December when it was not sold. Again in January lower cost by 20% and now costs 576 €. A. How much the goods stood originally? B, how much cost the goods after the first lowering? C, How many percents totally merchant l
• Together m+w
  Women 30%. Men are 360 more. How many are together?
• Former price
  The price of an article is cut by 10%, to restore it to the former value, by what percent the new price must be increased?
• Sum 10
  What is the probability that two dice throw twice in a row will result the sum of 10?
• Profit gain
  If 5% more is gained by selling an article for Rs. 350 than by selling it for Rs. 340, the cost of the article is:
• Adding percentages
  55%+36%+88%+71%+100=63% what is whole (X)? Percents can be added directly together if they are taken from the same whole, which means they have the same base amount. .. . You would add the two percentages to find the total amount.
• Walking
  Of the 450 students at the school, 432 walks to school. What percentage is this?
• The number 72
  The number 72 increase by 25%. By how much % will you have to reduce the number you created to get the number 72 again?
• Hiking trail
  The newly built hiking trail leads 25% through the field, 3/8 of the trail leads through the forest and the remaining 9 km along the river. How long is the train?
• Tabitha
  Tabitha manufactures a product that sells very well. The capacity of her facility is 241,000 units per year. The fixed costs are $122,000 per year and the variable costs are $11 per unit. The product currently sells for $17. a. What total revenue is req