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3 years ago

12

Utility company charges 12 cents per kilowatt hour of electricity what is the daily cost of keeping a 50 watt bulb on for 12 hou

rs each day

1 answer:

Sergio [31]3 years ago

6 0

Answer: 12 c · 0.6 = 7.2 c

Step-by-step explanation: one kilowatt hour is 1000 W·h

One bulb uses 12 h · 50 W = 600 Wh = 0,6 kWh

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Eight rooks are placed randomly on a chess board. What is the probability that none of the rooks can capture any of the other ro

Brums [2.3K]

Answer:

9.11*10^-4 %

Step-by-step explanation:

To find the probability, you simply need to find the possible outcomes that allows no rooks to be in danger, and the possible amount of ways to place the rooks.

For the first outcome, you start by putting 1 rook in the first columns, you have 8 possible rows to do this. The next rook in the next column will only have 7 possible rows, as you have to exclude the one where the previous rook is located. The next rook, 6 possibilities, the next 5, and so on. So we conclude that the total amount of ways so that none of the rooks can capture any of the other rooks is 8*7*6*5*4*3*2*1 = 8! = 40320

In order to find the total amount of ways to place the rooks, you can just use a combinatoric:

$\left[\begin{array}{ccc}64\\8\end{array}\right]= \frac{64!}{8!(64-8)!} = 4.43*10^9$

Then:

P = $\frac{40320}{4.43*10^9}*100\%=9.11*10^{-4}\%$

5 0

4 years ago

Nika rolls an 8-sided cube with faces numbered 1 through 8. Which of the following statements is true?

andreyandreev [35.5K]

Answer: Statement 2 (P(odd number) = 1/2) is true

Step-by-step explanation:

Statement 1: there are 4 even numbers (2, 4, 6, 8) so therefore a 1/2 chance, not a 1/8. [FALSE]

Statement 2: there are 4 odd numbers (1, 3, 5, 7) so therefore a 1/2 chance, so this is true. [TRUE]

Statement 3: 8 is the biggest number, so there are 7, not 1, numbers less than it. [FALSE]

Statement 4: there is no 9 on an 8 sided cube. [FALSE]

8 0

3 years ago

What is the difference? StartFraction 2 x 5 Over x squared minus 3 x EndFraction minus StartFraction 3 x 5 Over x cubed minus 9

Fiesta28 [93]

The expression which is equivalent to the difference of the given algebraic fraction is,

$\dfr\dfrac{(x+5)(x+2)}{x(x-3)(x+3)}$

<h3>What is the difference? </h3>

Difference is the mathematical operation in which the one number is subtract from another number.

To find the difference of two fraction numbers, we find the least common factor of denominator and write the all numbers as one fraction.

The given expression in the problem is,

$\dfrac{2x+5}{x^2-3x}-\dfrac{3x+5}{x^3-9x}-\dfrac{x+1}{x^2-9}$

Factorize the denominator of each term as,

$\dfrac{2x+5}{x(x-3)}-\dfrac{3x+5}{x(x-3)(x+3)}-\dfrac{x+1}{(x-3)(x+3)}$

Here, the least common factor of the denominators is x(x-3)(x+3), therefore, the expression can be written as,

$\dfrac{(x+3)(2x+5)-(3x+5)-(x)(x+1)}{x(x-3)(x+3)}\\\dfr\dfrac{2x^2+5x+6x+15-3x-5-x^2-x}{x(x-3)(x+3)}\\\dfr\dfrac{x^2+7x+10}{x(x-3)(x+3)}\\\dfr\dfrac{(x+5)(x+2)}{x(x-3)(x+3)}$

Hence, the expression which is equivalent to the difference of the given algebraic fraction is,

$\dfr\dfrac{(x+5)(x+2)}{x(x-3)(x+3)}$

Learn more about the difference of two fractions here;

brainly.com/question/13222

6 0

2 years ago

What is three fourths of a right angle

Usimov [2.4K]

3/4 x 90 degree = 67.5 degree

3 0

4 years ago

Read 2 more answers

Which graph best represents y=-x2 + 6 x - 1?

ryzh [129]

Answer:

Assuming

$y = -2x + 6x - 1\\y = 4x - 1$

Step-by-step explanation:

See Graph

6 0

3 years ago