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3 years ago

Four less than the product of a number and 7 is eight more than that number

Mathematics

1 answer:

hjlf3 years ago

8 0

Let the number be x, then 7x - 4 = x + 8
7x - x = 8 + 4
6x = 12
x = 12/6 = 2.

Therefore, the number is 2.

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Math help pls!! answer choices are 17.1 , 3.5 , 8.4 , and 1.5

Hoochie [10]

Triangles ABD and BCD are similar, because they are both right and share a common angle, and thus all three angles are equal.

This means that we can set the proportion

$AB\div AD = BC\div DC$

Plug the numbers and we have

$5\div 3.5 = 12\div x$

Solve for $x$ :

$x=\dfrac{12\cdot 3.5}{5}=8.4$

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3 years ago

Light travels <img src="https://tex.z-dn.net/?f=9.45%2A10%5E%7B15%7D" id="TexFormula1" title="9.45*10^{15}" alt="9.45*10^{15}" a

valentinak56 [21]

Answer:

300000000

Step-by-step explanation:

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3 years ago

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BigorU [14]

Answer:

24. because 2009-2005+20 = 24. hope that helps

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3 years ago

On a family outing, Tyler bought 5 cups of hot cocoa and 4 pretzels for $18.40. Some of his family

elena55 [62]

Answer:

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3 years ago

The probability that a lab specimen contains high levels of contamination is 0.14. A group of 4 independent samples are checked.

Shtirlitz [24]

Answer:

a) 0.5470 = 54.70% probability that none contain high levels of contamination.

b) 0.3562 = 35.62% probability that exactly one contains high levels of contamination.

c) 0.4530 = 45.30% probability that at least one contains high levels of contamination.

Step-by-step explanation:

For each sample, there are only two possible outcomes. Either they contain high levels of contamination, or they do not. The samples are independent. So we use the binomial probability distribution to solve this question.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

In which $C_{n,x}$ is the number of different combinations of x objects from a set of n elements, given by the following formula.

$C_{n,x} = \frac{n!}{x!(n-x)!}$

And p is the probability of X happening.

The probability that a lab specimen contains high levels of contamination is 0.14.

This means that $p = 0.14$

A group of 4 independent samples are checked.

This means that $n = 4$

(a) What is the probability that none contain high levels of contamination?

This is P(X = 0)

$P(X = 0) = C_{4,0}.(0.14)^{0}.(0.86)^{4} = 0.5470$

0.5470 = 54.70% probability that none contain high levels of contamination.

(b) What is the probability that exactly one contains high levels of contamination?

This is P(X = 1)

$P(X = 1) = C_{4,1}.(0.14)^{1}.(0.86)^{3} = 0.3562$

0.3562 = 35.62% probability that exactly one contains high levels of contamination.

(c) What is the probability that at least one contains high levels of contamination?

Either none of the samples contain high levels of contamination, or at least one does. The sum of the probabilities of these events is decimal 1. So

$P(X = 0) + P(X \geq 1) = 1$

We want to find $P(X \geq 1)$ . So

$P(X \geq 1) = 1 - P(X = 0) = 1 - 0.5470 = 0.4530$

0.4530 = 45.30% probability that at least one contains high levels of contamination.

8 0

3 years ago