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3 years ago

what is the cost of 8 books at $4 each? what is the cost of x books at $4 each? what is the cost of 5 books at $x each ?

Mathematics

1 answer:

tatiyna3 years ago

6 0

Step-by-step explanation:

the cost of 8 books at $4 each

=》8 × 4 = $ 32

the cost of x books at $4 each

=》x × 4 = $ 4x

the cost of 5 books at $x each

=》5 × x = $ 5x

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You measure the lifetime of a random sample of 25 rats that are exposed to 10 Sv of radiation (the equivalent of 1000 REM), for

Slav-nsk [51]

Answer:

CI 95%(μ)= [13.506 ; 14.094]

Step-by-step explanation:

The confidence interval (CI) formula is:

CI (1-alpha) (μ)= mean+- [(Z(alpha/2))* σ/sqrt(n)]

alpha= is the proportion of the distribution tails that are outside the confidence interval. In this case, 5% because 100-90%

Z(5%/2)= is the critical value of the standardized normal distribution. In this case is 1.96

σ= standard deviation. In this case 0.75 day

mean= 13.8 days

n= number of observations . In this case 25

Then, the confidence interval (90%) is:

CI 95%(μ)= 13.8+- [1.96*(0.75/sqrt(25)]

CI 95%(μ)= 13.8+- [1.96*(0.75/5) ]

CI 95%(μ)= 13.8+- (0.294)

CI 95%(μ)= [13.8-0.294 ; 13.8+0.294]

CI 95%(μ)= [13.506 ; 14.094]

4 0

3 years ago

What is the value of x:<br><br> 2 + x = 8

klio [65]

6

2+x=8
Subtract 2 on both sides
x=6

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IgorLugansk [536]

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What number is smaller number -5 or -15? Explain your answer. Please help college math basic algebra

Goryan [66]

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Question number 8. Prove that 3 + √5 is an irrational number.

Marina86 [1]

Answer :

Let's assume the opposite of the statement i.e., 3 + √5 is a rational number.

$\\ \sf \: 3 + \sqrt{5} = \frac{a}{b} \\ \\ \qquad \: \tiny \sf{(where \: \: a \: \: and \: \: b \: \: are \: \: integers \: \: and \: \: b \: \neq \: 0)} \\$

$\\ \sf \: \sqrt{5} = \frac{a}{b} - 3 = \frac{a - 3b}{b} \\$

Since, a, b and 3 are integers. So,

$\\ \sf \: \frac{p - 3b}{b} \\ \\ \qquad \tiny \sf{ \: (is \: \: a \: \: rational \: \: number \:) } \\$

Here, it contradicts that √5 is an irrational number.

because of the wrong assumption that 3 + √5 is a rational number.

$\\$

Hence, 3 + √5 is an irrational number.

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3 years ago

what is the cost of 8 books at $4 each? what is the cost of x books at $4 each? what is the cost of 5 books at $x each ?​

what is the cost of 8 books at $4 each? what is the cost of x books at $4 each? what is the cost of 5 books at $x each ?