4a + 6b = 10
2a - 4b = 12...multiply by -2
----------------
4a + 6b = 10
-4a + 8b = - 24 (result of multiplying by -2)
------------------add
14b = - 14
b = -14/14
b = -1
2a - 4b = 12
2a - 4(-1) = 12
2a + 4 = 12
2a = 12 - 4
2a = 8
a = 8/2
a = 4
so 12a = 12(4) = 48 <==
Answer: (80% , 85%)
Step-by-step explanation:
We know that, confidence interval for population proportion is given by :-
(p-E , p+E)
, where p = sample proportion , E = Margin of error.
Given : Proportion of elementary school teachers who are female = 82%.
The article also states the maximum error of their estimate = 3%.
Then, the 90% confidence interval for the proportion of elementary school teachers who are female will be :
(82%-2% , 82%+3%)
= (80% , 85%)
Hence, the resulting 90% confidence interval for the proportion of elementary school teachers who are female = (80% , 85%)
Answer:
- The system of equations is x + y = 85 and 7/20x+2/5y=31
- To eliminate the x-variable from the equations, you can multiply the equation with the fractions by 20 and multiply the other equation by -7.
- B-She used 60 minutes for calling and 25 minutes for data.
Step-by-step explanation:
It is always a good idea to start by defining variables in such a problem. Here, we can let x represent the number of calling minutes, and y represent the number of data minutes. The the total number of minutes used is ...
x + y = 85
The total of charges is the sum of the products of charge per minute and minutes used:
7/20x + 2/5y = 31.00
We can eliminate the x-variable in these equations by multiplying the first by -7 and the second by 20, then adding the result.
-7(x +y) +20(7/20x +2/5y) = -7(85) +20(31)
-7x -7y +7x +8y = -595 +620 . . . . eliminate parentheses
y = 25 . . . . . . . . simplify
Then the value of x is
x = 85 -y = 85 -25
x = 60
Answer:
63 students.
Step-by-step explanation:
x students.
34 have science 28 have math 5 math and science 6 neither.
6 neither means there were at least 6 students so our number goes up to 6 students.
34 have science 28 have math 5 have both.
34-5 and 28-5
29 and 23
29+23 is 52 +5 is 57 +6 is 63.
63 students.
HOpe this helps!
Merry Christmas!
Answer:
Step-by-step explanation:
Set this up as a proportion, with inches on the top and feet on the bottom for our scale. We will find the actual length first, then we'll find the width.
Cross multiply to get that the actual length is 5(2.5) = 12.5 feet. Now for the width:
Cross multiply to get that the actual width is 5(3) = 15 feet.
If you want the area of the room, multiply the length times the width to get
A = 15(12.5)
A = 187.5 feet squared
