Answer:
You are selecting marbles with replacement. The marble selections (trials) are independent and the marble selection follows the binomial distribution.
The probability of selecting a red marble the first time is 1313.
(This is because 4 out of 12 marbles are red and412412 reduces to 1313.
The probability of selecting a red marble the second time is 1313.
The marble selections are independent and you can multiply the two probabilities to get the following:
probability of getting 2 reds = (13)2(13)2
=19=19.
So the probability of getting two reds is 1919.
They didn’t multiply 7 by 12, making it seven dozen
Answer:
(2x+1)(x+3)
2x(x+3)+1(x+3)
2x2+6x+x+3
2x2+7x+3 (2x2 means two x square)
if you want you can also multiply 2x+3 by x+3
like this:
(2x+1)(x+3)
x(2x+1)+3(2x+1)
2x2+x+6x+3
2x2+7x+3 (2x2 means two x square)
They will both give you the same answer.
15/17. The value (ratio) of cos A is 15/17.
The trigonometric ratios of an acute angle are, basically, the sine, the cosine and the tangent. They are defined from an acute angle, α, of a right triangle, whose elements are the hypotenuse, the leg contiguous to the angle, and the leg opposite the angle.
-The sine of the angle is the opposite leg divided by the hypotenuse.
-The cosine of the angle is the adjacent leg divided by the hypotenuse.
-The tangent of the angle is the opposite leg divided by the adjacent leg or, which is the same, the sine of the angle divided by the cosine of the angle.
cos A = adjacent leg/hypothenuse = BC/AC = 15/17
