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3 years ago

Thuy rolls a number cube 7 times. which expression represents the probability of rolling a 4 exactly 2 times?

2 answers:

6 0

The result of rolling a number cube 7 times is a 7-digit number composed of digits 1,2,3,4,5 and 6 so that digits can repeat. The total number of possibilities is 6^7.

The number of possibilities where 4 appears exactly two times is 5^5*(7!-6!/2).
5^5 is the number of 5-digits numbers composed of digits 1,2,3,5 and 6 so that digits can repeat.
7! is the number of permutations of digits 1,2,3,4,4,5 and 6.
6! is the number of permutations of digits 1,2,3,{4,4},5 and 6.
We don't want to subtract all numbers where digits 4 appear side by side. That's why we must divide 6! by 2.

Finally, the probability is P=5^5(7!-6!/2)/7^7

mel-nik [20]3 years ago

5 0

Answer:

The answer is C I just took the test!!!!!!!

Step-by-step explanation:

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Gennadij [26K]

Answer:

30 feet is represented by 3 3/4 inches on the drawing

Step-by-step explanation:

We have the relation as;

1 inch = 8 feet

Thus;

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2 years ago

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Arte-miy333 [17]

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3 years ago

Help me please. Thank you if you do.

Daniel [21]

Answer:

See below

Step-by-step explanation:

Angle A is congruent to Angle C because of alternative interior angles

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2 years ago

Please help ASAP!!!Please explain your answer

nignag [31]

Answer:

Below

Step-by-step explanation:

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Hope this helps!

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3 years ago

Find the exact trigonometric ratios for the angle x whose radian measure is given. (if an answer is undefined, enter undefined.)

Inga [223]

Given the angle $\frac{3\pi}{4}$

angle $\frac{3\pi}{4}$ is equivalent to angle 135 degrees and angle 135 degrees is equvalent to angle 45 degrees in the second quadrant, thus sine is positive but cosine and tangent are negative.

$\sin \frac{3\pi}{4} =\sin \frac{\pi}{4} = \frac{1}{ \sqrt{2} } \\ \\ \csc\frac{3\pi}{4}= \frac{1}{\sin\frac{3\pi}{4}} = \frac{1}{\frac{1}{ \sqrt{2} }} = \sqrt{2} \\ \\ \cos\frac{3\pi}{4} =-\cos \frac{\pi}{4} = -\frac{1}{ \sqrt{2} } \\ \\ \sec\frac{3\pi}{4}= \frac{1}{\cos\frac{3\pi}{4}} = \frac{1}{-\frac{1}{ \sqrt{2} }} =- \sqrt{2} \\ \\ \tan\frac{3\pi}{4} =-\tan \frac{\pi}{4} = -1 \\ \\ \cot\frac{3\pi}{4}= \frac{1}{\tan\frac{3\pi}{4}} = \frac{1}{-1} =- 1$

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3 years ago