double counting

Huỳnh Anh Phương

28/08/2018 at 01:54

Jason has $8. He going the bookstore to buy 2 books. If each book cost 1 dollar; 2 quarters; 3 dimes; 2 nickel; 4 cents, how much money he has left ?

double counting

Huỳnh Anh Phương

19/08/2018 at 03:18

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Linda has 12 marbles. After play with Tony, she loses 3 marbles.

a) What fraction suppose number marbles Linda has left? Express your answer as a common fraction.

b) If in the first time Tony have 8 marbles, how many marbles will Tony have now?

double counting

Huỳnh Anh Phương

12/06/2018 at 12:31

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Anna has 708 strawberries. She uses 12 strawberries to make cake, 20 strawberries to make juice. What percent Anna have left?

double counting percentages

Nguyễn Mạnh Hùng 14/06/2018 at 02:10

After using strawberries to make cake and make juice, Anna's strawberries left is:

708-12-20=676(strawberries)

Anna is only has:

676:708$\approx0,95=95\%$
Huỳnh Anh Phương selected this answer.

huynh anh phuong

31/05/2018 at 10:19

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If a and b are prime number , a is smaller than 110 and bigger than 99 and b is the greatest 1-digit number, whats is the total ?

double counting

Nguyễn Mạnh Hùng 14/06/2018 at 08:22

According to the title, we have:

99<a<110 and a is a prime number

So a=103

b is the greatest 1-digit number so b = 9

a+b=103+9=112

huynh anh phuong

12/12/2017 at 10:59

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There are many people in the party, in the party has 4 tables, each tables have 3 plates, each plates has 9 pancakes. How many people in the party?

double counting

Lê Quốc Trần Anh Coodinator 29/12/2017 at 18:00

The title is missing some information: Each person has a pancake.

So there are: $4.3.9=108\left(people\right)$ in the party.
FA Liên Quân Garena 30/12/2017 at 21:44

The title is missing some information: Each person has a pancake.

So there are: 4.3.9=108(people)

in the party.
nguyen tuan anh 06/04/2018 at 13:48

the title is missing some information : Each person has a pancake

so there are : 4.3.9 = 108 (people) in the party

Đỗ Phi Phi

26/07/2017 at 21:39

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A prime number is called a jillyprime when doubling it and adding 1 results in another prime. How many numbers lass than 15 are jillyprimes? (Note that 1 is not a prime.)

Prime Numbers and Composite Numbers double counting adding

Phan Thanh Tinh Coodinator 26/07/2017 at 23:34

2 x 2 + 1 = 5

3 x 2 + 1 = 7

5 x 2 + 1 = 11

7 x 2 + 1 = 15

11 x 2 + 1 = 23

13 x 2 + 1 = 27

So,there are 4 jillyprimes which are less than 15 : 2 ; 3 ; 5 ; 11
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FA KAKALOTS 28/01/2018 at 22:04

2 x 2 + 1 = 5

3 x 2 + 1 = 7

5 x 2 + 1 = 11

7 x 2 + 1 = 15

11 x 2 + 1 = 23

13 x 2 + 1 = 27

So,there are 4 jillyprimes which are less than 15 : 2 ; 3 ; 5 ; 11

A house has 10 rooms. Ten boys stay in different rooms and count the number of doors in them. After that they sum all results and receive 25. What a proposition can't be true about number N of doors which led outside the house?

double counting

tth 30/10/2017 at 15:14

We have:

25 do not divide to 10

So 25 can't be true about number N of doors .

Note: I'm not certain
Ma Kết 05/04/2018 at 14:42

We have:

25 do not divide to 10

So 25 can't be true about number N of doors .

Note: I'm not certain
Ma Kết 05/04/2018 at 14:41

Hà Đức Thọ

falcon handsome moderators

09/03/2017 at 12:34

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Let the answer be k . We count the total number of paris of students were on duty together in the k days. Since every pair of students was on duty together exactly once, this is equal to $C^{15}_2$ x 1 = 105. On the other hand, since 3 students were on duty per day, this is also equal to $C^3_2$ x k = 3k. Hence 3k = 105 and so k = 35

double counting