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marysya [2.9K]
3 years ago
7

At the karate school, Class A has 8 students with an average age of 6 years. Class B has 12 students with an average age of 9 ye

ars. The classes combine for a group workout.
What is the average age of the combined classes?

Enter your answer as a decimal in the box.
Mathematics
2 answers:
Murrr4er [49]3 years ago
7 0

Answer: I took the test and the answer is 7.8

Good luck!

ELEN [110]3 years ago
3 0
IT IS 7.8 AND I  KNOW IT IS RIGHT
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Are 2/3 and 6/8 equivalent?
miskamm [114]
No they are not, 6/8 could also be represented as 3/4. Therefore they are not equivalent. You would divide each side by the factor they have in common such as 2.
7 0
3 years ago
A ball is projected in to the air. Its height at time t is given by the equation
Ksju [112]
The equation gives the height of the ball. That is, h is the height of the ball. t is the time. Since we are looking for the time at which the height is 8 (h=8), we need to set the equation equal to 8 and solve for t. We do this as follows:

h=-16 t^{2} +60t+1
8=-16 t^{2} +60t+1
16 t^{2} -60t-1+8=0
16 t^{2} -60t+7=0

This is a quadratic equation and as it is set equal to 0 we can solve it using the quadratic formula. That formula is:
t= \frac{-bplus minus \sqrt{ b^{2}-4ac } }{2a}
You might recall seeing this as "x=..." but since our equation is in terms of t we use "t-=..."

In order to use the formula we need to identify a, b and c.
a = the coefficient (number in front of) t^{2} = 16.
b = the coefficient of t = -60
c = the constant (the number that is by itself) = 7

Substituting these into the quadratic formula gives us:
t= \frac{-(-60)plus minus \sqrt{ (-60)^{2}-4(16)(7) } }{2(16)}
t= \frac{60plus minus \sqrt{3600-448 } }{32}
t= \frac{60plus minus \sqrt{3152 } }{32}

As we have "plus minus" (this is usually written in symbols with a plus sign over a minus sign) we split the equation in two and obtain:
t=  \frac{60+56.1426}{32} =3.63
and
t=  \frac{60-56.1426}{32} =.12

So the height is 8 feet at t = 3.63 and t=.12

It should make sense that there are two times. The ball goes up, reaches it's highest height and then comes back down. As such the height will be 8 at some point on the way up and also at some point on the way down.


3 0
3 years ago
The bottom of the ladder on a horizontal flat surface rests against a wall. It makes an angle of elevation of 39°. The bottom of
rewona [7]
Cosα=x/L

L=x/cosα, we are told that the ladder base is 48 ft from the base of the wall and α=39° so:

L=48/cos39 ft

L≈61.76 ft (to nearest hundredth of a foot)
5 0
2 years ago
What is 5 11/10 simplified
lbvjy [14]

Answer:

61/10 or in decimal form 6.1 or 6 1/10

Step-by-step explanation:

3 0
2 years ago
BOI I NEED HALP SO MUCH: What is 2308942930/23049930 as a common fraction simplified
nordsb [41]
The answer is <span>768331/</span>76964765
7 0
2 years ago
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