Answer:
And if we use the normal standard distribution or excel we got:
Step-by-step explanation:
For this case we have the following info given:
represent the mean
represent the standard deviation
represent the sample size
The distribution for the sample size if we use the central limit theorem (n>30) is given by:
And for this case we want to find the following probability:
And for this case we can use the z score formula given by:
And replacing we got:
And if we use the normal standard distribution or excel we got:
Answer:
f = 3
Step-by-step explanation:
Solve for f:
13 - 6 f = 2 f - 11
Subtract 2 f from both sides:
13 + (-6 f - 2 f) = (2 f - 2 f) - 11
-6 f - 2 f = -8 f:
-8 f + 13 = (2 f - 2 f) - 11
2 f - 2 f = 0:
13 - 8 f = -11
Subtract 13 from both sides:
(13 - 13) - 8 f = -13 - 11
13 - 13 = 0:
-8 f = -13 - 11
-13 - 11 = -24:
-8 f = -24
Divide both sides of -8 f = -24 by -8:
(-8 f)/(-8) = (-24)/(-8)
(-8)/(-8) = 1:
f = (-24)/(-8)
The gcd of -24 and -8 is -8, so (-24)/(-8) = (-8×3)/(-8×1) = (-8)/(-8)×3 = 3:
Answer: f = 3
If Eric plays piano, then David will sing.
As soon as I read this, the words "law of cosines" popped
into my head. I don't have a good intuitive feeling for the
law of cosines, but I went and looked it up (you probably
could have done that), and I found that it's exactly what
you need for this problem.
The "law of cosines" relates the lengths of the sides of any
triangle to the cosine of one of its angles ... just what we need,
since we know all the sides, and we want to find one of the angles.
To find angle-B, the law of cosines says
b² = a² + c² - 2 a c cosine(B)
B = angle-B
b = the side opposite angle-B = 1.4
a, c = the other 2 sides = 1 and 1.9
(1.4)² = (1)² + (1.9)² - (2 x 1 x 1.9) cos(B)
1.96 = (1) + (3.61) - (3.8) cos(B)
Add 3.8 cos(B) from each side:
1.96 + 3.8 cos(B) = 4.61
Subtract 1.96 from each side:
3.8 cos(B) = 2.65
Divide each side by 3.8 :
cos(B) = 0.69737 (rounded)
Whipping out the
trusty calculator:
B = the angle whose cosine is 0.69737
= 45.784° .
Now, for the first time, I'll take a deep breath, then hold it
while I look back at the question and see whether this is
anywhere near one of the choices ...
By gosh ! Choice 'B' is 45.8° ! yay !
I'll bet that's it !
Sixty eight trillion, eight hundred sixty billion, five hundred million, eighty six thousand and six
