1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
aliya0001 [1]
3 years ago
12

Suppose there are 200 lockers and 200 students. Kayla reasons that since there are 10

Mathematics
1 answer:
Rus_ich [418]3 years ago
5 0

Answer:

Kayla's reasoning is not correct.

Step-by-step explanation:

The locker problem is as follows:

Imagine you are at a school that has student lockers. There are 200 lockers, all shut and unlocked, and 200 students. Suppose the first student goes along the row and opens every locker. The second student then goes along and shuts every other locker beginning with number 2. The third student changes the state of every third locker beginning with number 3. (If the locker is open the student shuts it, and if the locker is closed the student opens it). The fourth student changes the state of every fourth locker beginning with number 4. Imagine that this continues until the 200 students have followed the pattern with the 200 lockers. At the end, which lockers will be open and which will be closed? Why?

Solution:

So from the information we know that the first student goes along the row and opens every locker.

Then the second student shuts every other locker, i.e. locker numbers 2, 4, 6, 8, 10, ..., 196, 198 and 200.

Then the third students changes the state of every third locker, i.e. he/she closes an open locker and opens a closed locker.

So the open lockers are: 1, 5, 6, 12,...

Then the fourth students changes the state of every fourth locker.

So the open lockers are: 1, 4, 5, 6, 8,....

So, on we will observe that the open lockers have a perfect square number such as, 1, 4, 9, 16,....

Consider that the pattern is as follows:

Student 1 opens the locker, Student 2 closes it, Student 3 opens it, person 4 Student and so on.

This is because the square numbers always have an odd number of factors, which leads them to be open at the end.

Take any locker number, 40, for example. Its state (open or closed) is changed for every student whose number in line is a factor of the locker number.

Student      Locker 40 status

     1                    Open

     2                   Close

     4                   Open

     5                   Close

     8                   Open

     10                  Close

    20                  Open

    40                  Close

Like all other lockers numbered with non-square numbers, it ends up closed after all the students have gone through the line because it has an even number of factors.

Consider the locker number 16:

Student      Locker 16 status

     1                    Open

     2                   Close

     4                   Open

     8                   Close

     16                  Open

Thus, we can conclude that all the doors with square numbers on them will remain open because all square numbers have an odd number of factors and the doors with non-square numbers on them will remain close because they have even number of factors.

There will be a total of 14 lockers open.

1, 4, 9, 16, 25, 36, 49, 64, 81, 100, 121, 144, 169 and 196

So, if there are 10 lockers open in the first 100 lockers there must be only 4 other lockers opened in the next 100.

You might be interested in
A pebble drops from a balcony that is 160 feet above the ground. The pebble lands on the top of a sign that is 16 feet high. The
MA_775_DIABLO [31]

Answer:

3 seconds

Step-by-step explanation:

16 = 160 - 16t²

16t² = 144

t² = 9

t = 3

7 0
3 years ago
Freeeeeeeeeeee points taken them plz dont report sorry if you didnt get points
Kay [80]

Answer:

wait no, THANK YOUU <333

Step-by-step explanation:

4 0
3 years ago
Read 2 more answers
What is the value of K?
sladkih [1.3K]

Answer: its A

Step-by-step explanation:

Because

3 0
3 years ago
X+9=2x-3<br> FIND THE X!!!!!!
Ierofanga [76]

Answer:

x = 12

Step-by-step explanation:

<u>To find "x"</u>, we need to <u>isolate it</u>. This means move "x" to the left side, and everything else to the right side.

When moving a number, do its <u>reverse operation</u> to the entire equation.

x + 9 = 2x - 3

x - 2x + 9 = 2x - 2x - 3         Subtract 2x from both sides

-x + 9 = -3                              

-x + 9 - 9 = -3 - 9           Subtract 9 from both sides

-x = -12

-x/-1 = -12/-1          Divide both sides by -1 to get rid of the negatives

x = 12                     Final answer

Check your answer. Split the equation for the left and right sides. Substitute "x" for the answer "12".

LS:   (left side)

x + 9

= 12 + 9              Add

= 21

RS:   (right side)

2x - 3

= 2(12) - 3            Multiply before subtracting

= 24 - 3               Subtract

= 21

Both sides equal to 21 when "x" is 12.

LS = RS          left side equals right side

Therefore the answer is correct.

3 0
3 years ago
The four angles of a quadrilateral are in the ratio 2:3:5:8. Find the angles
sp2606 [1]

Answer:

Step-by-step explanation: let 2:3:5:8 be 2x,3x,5x,8x respectively .

*angles in a quadrilateral is 360 degree

*2x+3x+5x+8x=360

*18x=360

*x=360/18

*x=20

now substitute x in these:

2x=2x20=40

3x=3x20=60

5x=5x20=100

8x=8x20= 160

so these are the following angles: 40,60,100 and 160

8 0
3 years ago
Other questions:
  • The perimeter of the triangular park on the right is 16x-6. What is the missing length? The bottom side length is 5x+4 and the r
    10·1 answer
  • How would you describe the slice that created the triangular cross-section on this cake?
    13·2 answers
  • Factor the polynomial completely using the
    7·2 answers
  • MP bisects ∠BMS. If m∠BMP = 2x + 9 and m∠BMS = 7x – 3, find the value of m∠PMS
    9·1 answer
  • Anyone know how to do it?
    6·1 answer
  • On a string of lights for every 6 green lights,there are 4 white lights.If their are 30 green lights,how many white lights are t
    14·2 answers
  • One half of a number is eight
    14·1 answer
  • Simplify 7.2×10 to the power-3 - 9.5×10 to the power -5 plz step by step​
    12·1 answer
  • Population data from three towns is displayed in the tables below. Which town has growth that follows an exponential model?
    12·1 answer
  • A researcher is studying the growth of bacteria. He starts eith 280 of the bacteria. It grows continuously at a rate of 6% per h
    9·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!