Examination

The class is 21 students. How many ways can choose two to examination?

Result

n =  210

Solution:

Solution in text n =







Leave us a comment of example and its solution (i.e. if it is still somewhat unclear...):

Showing 0 comments:
1st comment
Be the first to comment!
avatar




To solve this example are needed these knowledge from mathematics:

Would you like to compute count of combinations?

Next similar examples:

  1. 2nd class combinations
    color_circle From how many elements you can create 4560 combinations of the second class?
  2. Commitee
    committees A class consists of 6 males and 7 females. How many committees of 7 are possible if the committee must consist of 2 males and 5 females?
  3. Internet anywhere
    normal_d_4 In school, 60% of pupils have access to the internet at home. A group of 8 students is chosen at random. Find the probability that a) exactly 5 have access to the internet. b) At least 6 students have access to the internet
  4. Math logic
    children_7 There are 20 children in the group, each two children have a different name. Alena and John are among them. How many ways can we choose 8 children to be among the selected A) was John B) was John and Alena C) at least one was Alena, John D) maximum one w
  5. Chocolates
    Chocolate In the market have 4 kinds of chocolates. How many ways can we buy 19 chocolates?
  6. Boys and girls
    dices2_10 There are 11 boys and 18 girls in the classroom. Three pupils will answer. What is the probability that two boys will be among them?
  7. Pairs
    dvojice From the five girls and four boys teachers have to choose one pair of boy and girl. A) How many such pairs of (M + F)? B) How many pairs where only boys (M + M)? C) How many are all possible pairs?
  8. A pizza
    pizza_11 A pizza place offers 14 different toppings. How many different three topping pizzas can you order?
  9. N-gon
    ngon How many diagonals has convex 11-gon?
  10. Party
    party-informatikov At party overyone clink with everyone. Together, they clink 171 times. How many people were at the party?
  11. Lines
    lines_1 In how many points will intersect 14 different lines, where no two are parallel?
  12. Family
    family_32 94 boys are born per 100 girls. Determine the probability that there are two boys in a randomly selected family with three children.
  13. Three numbers
    dices2_9 We have three different non-zero digits. We will create all 3 digits numbers from them to use all 3 figures in each number. We add all the created numbers, and we get the sum of 1554. What were the numbers?
  14. Word
    words What is the probability that a random word composed of chars T, H, A, M will be MATH?
  15. Sales
    tesco From statistics of sales goods, item A buy 51% of people and item B buys 59% of people. What is the probability that from 10 people buy 2 item A and 8 item B?
  16. Family
    stork_bocian What is the probability that a family with 7 childrens have: exactly 5 girls? 7 girls and 0 boys? Consider the birth probability of a girl is 48.69% and boy 51.31%.
  17. Bulbs
    bulb The probability that the bulb can operate 5000 hours is 0.16. What is the probability that exactly one of three bulbs can operate 5000 hours?