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user100 [1]
3 years ago
6

A radio active isotope decays according to the exponential decay equation where t is in days. Round to the thousandths place. Th

e half life is the solution (t) of the equation: a/2=ae^-2.360t
Mathematics
1 answer:
Whitepunk [10]3 years ago
8 0
To calculate the value of the half life we proceed as follows;
a/2=ae^(-2.360t)
the a(s) will cancel and we shall remain with:
1/2=e^-2.360t
introducing the natural logs we get:
ln (1/2)=ln e^(-2.360t)
ln(1/2)=-2.360t
hence;
t=(ln 0.5)/(-2.360)
t=0.294
the answer is t=0.294
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Paul [167]
4 (2x – 3)= 2( 3x + 1)
<span>(4 (2x – 3)= 2( 3x + 1)) </span>÷ 2
2 (2x – 3) = (3x + 1)
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8 0
3 years ago
A grocery store’s receipts show that Sunday customer purchases have a skewed distribution with a mean of 27$ and a standard devi
34kurt

Answer:

(a) The probability that the store’s revenues were at least $9,000 is 0.0233.

(b) The revenue of the store on the worst 1% of such days is $7,631.57.

Step-by-step explanation:

According to the Central Limit Theorem if we have a population with mean μ and standard deviation σ and we take appropriately huge random samples (n ≥ 30) from the population with replacement, then the distribution of the sum of values of X, i.e ∑X, will be approximately normally distributed.  

Then, the mean of the distribution of the sum of values of X is given by,  

 \mu_{X}=n\mu

And the standard deviation of the distribution of the sum of values of X is given by,  

\sigma_{X}=\sqrt{n}\sigma

It is provided that:

\mu=\$27\\\sigma=\$18\\n=310

As the sample size is quite large, i.e. <em>n</em> = 310 > 30, the central limit theorem can be applied to approximate the sampling distribution of the store’s revenues for Sundays by a normal distribution.

(a)

Compute the probability that the store’s revenues were at least $9,000 as follows:

P(S\geq 9000)=P(\frac{S-\mu_{X}}{\sigma_{X}}\geq \frac{9000-(27\times310)}{\sqrt{310}\times 18})\\\\=P(Z\geq 1.99)\\\\=1-P(Z

Thus, the probability that the store’s revenues were at least $9,000 is 0.0233.

(b)

Let <em>s</em> denote the revenue of the store on the worst 1% of such days.

Then, P (S < s) = 0.01.

The corresponding <em>z-</em>value is, -2.33.

Compute the value of <em>s</em> as follows:

z=\frac{s-\mu_{X}}{\sigma_{X}}\\\\-2.33=\frac{s-8370}{316.923}\\\\s=8370-(2.33\times 316.923)\\\\s=7631.56941\\\\s\approx \$7,631.57

Thus, the revenue of the store on the worst 1% of such days is $7,631.57.

5 0
3 years ago
Write an equivalent expression for (x - 11)(x + 9).
vodka [1.7K]

Answer:

x²-2x-99

Step-by-step explanation:

(x-11)(x+9) - foil method

x times x = x squared

x times 9 = 9x

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-11 times 9 = -99

x squared + 9x + 11x + -99

x squared-2x-99

7 0
3 years ago
A store receives a shipment of 5,000 MP3 players. In a previous shipment of 5,000 MP3 players, 300 were
stepan [7]

The sample was 10 numbers.

4 of the numbers are less than 301.

So 4 out of 10 would be defective.

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He would expect 40% to be defective.

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3 years ago
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Leokris [45]

Answer:

Step-by-step explanation:

Solution :  

hello :

note :

Use the point-slope formula.

y - y_1 = m(x - x_1)   when : x_1= -1      y_1= 5  

     m= the slope is : (YC - YA)/(XC -XA)

(-1-2)/(0-3) = -3/-3 =1

( parallel to AC means same slope)

an equation in the point-slope form is : y -5 = 1(x+1)

y=x+6

6 0
2 years ago
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