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skad [1K]
3 years ago
7

the first group of students consists of 10 and their average age was 13 years old the next group consisted of 30 students and th

eir average was 9 years old find the average age of both groups?
Mathematics
1 answer:
Kazeer [188]3 years ago
4 0

Answer: The average was 9 years old find the average age of both groups is 10 years old.

Step-by-step explanation:

Formula foe average : \text{Average} =\dfrac{\text{Sum of all observations}}{\text{Number of observations}}

Given : The first group of students consists of 10 and their average age was 13 years old.

i.e. 13=\dfrac{\text{Sum of ages of students of first group}}{10}\\\\\Rightarrow\ \text{Sum of ages of students of first group}=13\times10=130      (1)

The next group consisted of 30 students and their average was 9 years old.

i.e. 9=\dfrac{\text{Sum of ages of students of next group}}{30}\\\\\Rightarrow\ \text{Sum of ages of students of nextgroup}=9\times30=270      (2)

Then from (1) and (2) , the sum of both groups (first group and next group )students = 130+270 =400

Combined students of both groups (first and next group )= 10+30=40

Now , the average of both groups =\dfrac{\text{Sum of combined students}}{\text{combined students}}

=\dfrac{400}{40}=10

Hence, the average was 9 years old find the average age of both groups is 10 years old.

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10. The sum of the digits of a three-digit number is 11. If the digits are reversed, the new number is 46
Zarrin [17]

Answer:

hope this helps

Step-by-step explanation:

The sum of the digits of a three-digit number is 11.

If the digits are reversed, the new number is 46 more than five times the old number.

If the hundreds digit plus twice the tens digit is equal to the units digit, then what is the number?

:

Write an equation for each statement:

:

"The sum of the digits of a three-digit number is 11."

x + y + z = 11

:

The three digit number = 100x + 10y + z

The reversed number = 100z + 10y + x

:

" If the digits are reversed, the new number is 46 more than five times the old number."

100z + 10y + x = 5(100x + 10y + z) + 46

100z + 10y + x = 500x + 50y + 5z + 46

combine on the right

0 = 500x - x + 50y - 10y + 5z - 100z + 46

499x + 40y - 95z = -46

:

"the hundreds digit plus twice the tens digit is equal to the units digit,"

x + 2y = z

x + 2y - z = 0

:

Three equations, 3 unknowns

:

x + y + z = 11

x +2y - z = 0

-----------------Addition eliminates z

2x + 3y = 11

From the 2nd equation statement, we know that the 1st original digit has to be 1

2(1) + 3y = 11

3y = 11 - 2

3y = 9

y = 3 is the 2nd digit

then

1 + 3 + z = 11

z = 11 - 4

z = 7

:

137 is the original number

:

:

Check solution in the 2nd statement

If the digits are reversed, the new number is 46 more than five times the old number."

731 = 5(137) + 46

731 = 685 + 46

7 0
3 years ago
Choose all the numbers that 810 is divisible by.
Aleks04 [339]
810/2= 405

810/3= 270

810/4= 202.5 (not this one)

810/5= 162

810/6= 135

810/7= 115.71 ( not this one)

810/8= 101.25 (not this one)

810/9= 90

810/10= 81

810/11= 73.63 (not this one)

I hope this helps you!
3 0
3 years ago
Pls help being timmed
k0ka [10]

She buys 10kg

hope this helps

6 0
3 years ago
Read 2 more answers
Is 3/10 greater than or less than 1/2
V125BC [204]
To compare two fraction we have to make common denominator, then we can compare numerators.
Lets do this
\frac{1}{2}= \frac{1*5}{2*5}= \frac{5}{10}
Now we can compare numeratos.
3<5, so 1/2 is greater than 3/10.
8 0
3 years ago
Read 2 more answers
I HAVE 110,000 rolls of film, each roll of film weighs 4.70 ounces. How much would it cost me to have them moved at $0.46 per po
Elena-2011 [213]

Answer:

1 798 260.87$

Step-by-step explanation:

1 ounce =0.0625 pounds

110000×4.70=51700 ounces

51700:0.0625=827200 pounds

827200:0.46=1798260.869 $

=1798260.87 $

3 0
3 years ago
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