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
11Alexandr11 [23.1K]
3 years ago
13

Mrs. Smith's class is working on a variety of science experiments. Each

Mathematics
1 answer:
SVETLANKA909090 [29]3 years ago
8 0

Answer:

66

Step-by-step explanation:

If there are  <em>n</em>  students, then the number of pairs is \frac{n(n-1)}{2}.

With 12 students, \frac{12(12-1)}{2} = \frac{132}{2}=66 pairs can be formed.

The reason the formula works is this:  Each of the 12 students can be paired with 11 other students (no student is paired with him/her self).  But counting 12 x 11 = 132  counts each pair <u>twice</u>.  Example: student A can be paired with student B,..., student B can be paired with student A.  The pair was counted two times.

See the attached image that shows pairings of 5 students.  There are

5(5 - 1)/2 = 5(4)/2 = 10 pairs.

You might be interested in
Please help Explanation will be appreciated thanks,
Genrish500 [490]

Answer: A; 6.3%

Step-by-step explanation:

Problem 1

For the first problem, we first want to find y so that we can plug it into the expression.

We can use elimination method for the system of equations to solve.

3x+3y=21

3x-y=5

We subtract both equations to eliminate x.

4y=16                                        [divide both sides by 4]

y=4

Now that we know y, we can plug it into the expression.

\frac{4}{2} -3                                         [divide]

2-3                                         [subtract]

-1

We know that the answer is A.

--------------------------------------------------------------------------------------------------------

Problem 2

For the second problem, we need to know how to calculate percent error. The formula for precent error is \frac{|measured-exact|}{exact} *100%. We know that the exact value is 80 because the buyer was supposed to given 80. 75 is the measured value because that was what the buyer was given.

\frac{|75-80|}{80} *100%                               [subtract]

\frac{|-5|}{80} *100%                                   [solve absolue value]

\frac{5}{80} *100%                                     [divide]

0.0625*100%                               [multiply]

6.25

Since the problem said to round to one decimal place, we know that the answer is 6.3%.

4 0
3 years ago
What are the answers to these thank you and please tell me how to get it
mote1985 [20]
5-3(1/2x+2)=-7
-3(1/2x+2)=-7-5
(1/2x+2)=4
1/2x=2
x=4
just to give u an idea
4 0
3 years ago
Why do scientists use percentages less than 1
olganol [36]
They use percents less than one to get the the exact number
3 0
3 years ago
If a hallway measuring 90 feet by 7 feet requires 1/2 a fluid ounce of cleaning solution per square foot, how much cleaning solu
kirill115 [55]
90ft by 7ft gives an area of:
90 x 7 = 630 sq ft

1/2 fl oz is needed for each square foot

630 x 1/2 = 315 fl oz required.
4 0
3 years ago
HELP QUICK PLS WILL GIVE BRAINLIEST
alexandr1967 [171]

Answer:

0.08(50h)

Step-by-step explanation:

0.08(50h)+50h=

8/100(50h)+50h=

0.08(50h)+50h

It's 0.08 of 50h, so

0.08(50h)

4 0
3 years ago
Other questions:
  • How do you compare fractions decimals and percents?
    6·2 answers
  • Help meee please I need the answer
    9·2 answers
  • How many solutions are there to the equation below 15x+11=8x
    7·2 answers
  • Write an expression for the sequence of operations described below.
    10·1 answer
  • My math question to u<br><br>4 - 6x = 8
    6·2 answers
  • The distance covered by one step is 2.5 feet long. how many steps would the average person take to travel 50 feet
    5·2 answers
  • To stay properly hydrated, a person should drink 32 ounces of water for every 60 minutes of exercise. How much water should Damo
    12·1 answer
  • What's the rule?<br> 25, 20, 15, 10
    5·2 answers
  • I need help plz, i will give brainliest for the correct answer
    11·1 answer
  • Help plsssssssssssss
    7·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!