Step-by-step explanation:
1. P(pen then pencil) = 15/25 × 10/25 = 3/5 × 2/5 = 6/25
2. P(pen then pencil) + P(pencil then pen) = 6/25 + 6/25 = 12/25
3. P(pencil then pencil) = 10/25 × 10/25 = 2/5 × 2/5 = 4/25
4. P(at least 1 pen) = 1 − P(no pen) = 1 − 4/25 = 21/25
Multiply. 4 X 12 = 48. you need 48 people to make 4 teams
Solution: We are given that:
5 people can paint 7 walls in 21 minutes
Therefore, 1 person can paint 7 walls in
minutes
Which means 1 person can paint 1 wall in
minutes
Now, 3 people can paint 1 wall in
minutes
Therefore, 3 people can paint 5 walls in
minutes
Using a system of equations, it is found that <u>since the solution of the system does not involve decimal numbers</u>, it is possible to arrange the books in this way.
For the system, we consider that:
- x is the number of books on the first shelf.
- y is the number of books on the second shelf.
- z is the number of books on the third shelf.
In total, there are 152 books, hence:

The first shelf has 7 fewer books than the second shelf, hence:

Also, it has 11 more books than the third shelf, hence:

Then:


Then, replacing in the first equation:





The number of books in each shelf has to be countable, that is, cannot be decimal.
- Then, <u>since the solution of the system does not involve decimal numbers</u>, it is possible to arrange the books in this way.
To learn more about system of equations, you can take a look at brainly.com/question/14183076
Answer: 81
Concept:
When a number is being squared, to being put to any power, it means the number multiplies itself by the amount of times indicated by the exponent.
For example, if 3 is to the 3rd power, then it would appear to be 3 × 3 × 3.
Solve:
<u>Given</u>
9²
<u>Simplify exponents</u>
=9 × 9
<u>Simplify by multiplication</u>
=
Hope this helps!! :)
Please let me know if you have any questions