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anzhelika [568]
2 years ago
15

An element with mass 430 grams decays by 27.4% per minute. How much of the element is remaining after 19 minutes, to the nearest

10th of a gram?
Mathematics
1 answer:
nadya68 [22]2 years ago
7 0
The equation for exponential decay is y=a*b^x, where <em>a</em> is the initial amount, <em>b</em> = 1 + <em>r</em> (the growth rate as a decimal number) and <em>x</em> is the number of time periods (in this case, minutes).  Substituting the information we have:
y=430(1+-0.274)^1^9&#10;\\=430(1-0.274)^1^9&#10;\\=430(0.726)^1^9=0.98.  To the nearest tenth of a gram, this would be 1.0 grams.
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A machine fills boxes weighing Y lb with X lb of salt, where X and Y are normal with mean 100 lb and 5 lb and standard deviation
Bas_tet [7]

Answer:

Option b. None is the correct option.

The Answer is 63%

Step-by-step explanation:

To solve for this question, we would be using the z score formula

The formula for calculating a z-score is given as:

z = (x-μ)/σ,

where

x is the raw score

μ is the population mean

σ is the population standard deviation.

We have boxes X and Y. So we will be combining both boxes

Mean of X = 100 lb

Mean of Y = 5 lb

Total mean = 100 + 5 = 105lb

Standard deviation for X = 1 lb

Standard deviation for Y = 0.5 lb

Remember Variance = Standard deviation ²

Variance for X = 1lb² = 1

Variance for Y = 0.5² = 0.25

Total variance = 1 + 0.25 = 1.25

Total standard deviation = √Total variance

= √1.25

Solving our question, we were asked to find the percent of filled boxes weighing between 104 lb and 106 lb are to be expected. Hence,

For 104lb

z = (x-μ)/σ,

z = 104 - 105 / √25

z = -0.89443

Using z score table ,

P( x = z)

P ( x = 104) = P( z = -0.89443) = 0.18555

For 1061b

z = (x-μ)/σ,

z = 106 - 105 / √25

z = 0.89443

Using z score table ,

P( x = z)

P ( x = 106) = P( z = 0.89443) = 0.81445

P(104 ≤ Z ≤ 106) = 0.81445 - 0.18555

= 0.6289

Converting to percentage, we have :

0.6289 × 100 = 62.89%

Approximately = 63 %

Therefore, the percent of filled boxes weighing between 104 lb and 106 lb that are to be expected is 63%

Since there is no 63% in the option, the correct answer is Option b. None.

3 0
2 years ago
A ball is thrown upward and outward from a height of 77 feet. the height of the​ ball, f(x), in​ feet, can be modeled by f left
Oksi-84 [34.3K]
From the given function modeling the height of the ball:
f(x)=-0.2x^2+1.4x+7
A] The maximum height of the ball will be given by:
At max height f'(x)=0
from f(x), 
f'(x)=-0.4x+1.4
solving for x we get:
-0.4x=-1.4
x=3.5ft
thus the maximum height would be:
f(3.5)=-0.2(3.5)^2+1.4(3.5)+7
f(3.5)=9.45 ft

b]
How far from where the ball was thrown did this occur:
from (a), we see that at maximum height f'(x)=0
f'(x)=-0.4x+1.4
solving for x we get:
-0.4x=-1.4
x=3.5ft
This implies that it occurred 3.5 ft from where the ball was thrown.


 c] How far does the ball travel horizontally?
f(x)=-0.2x^2+1.4x+7
evaluationg the expression when f(x)=0 we get:
0=-0.2x^2+1.4x+7
Using quadratic equation formula:
x=-3.37386 or x=10.3739
We leave out the negative and take the positive answer. Hence the answer 10.3739 ft horizontally.
6 0
2 years ago
0.58 divided into 0.5568
Fiesta28 [93]
The answer to that would be 1.04166667.
3 0
2 years ago
Given 1 mile ≈ 1.6 kilometers, what is the standard deviation in kilometers? (enter your answer to two decimal places.)
nignag [31]

You recorded the weekly distance you bicycled in miles and computed the standard deviation to be s= 3.1 miles. your friend wants to know the standard deviation in kilometers. Do you need to redo all the calculations?

No need to redo all the calculations. we use the given standard deviation. We convert the given standard deviation miles into kilometers.

Given 1 mile ≈ 1.6 kilometers

So 3 miles = 1.6 * 3.1 = 4.96 kilometers

standard deviation = 4.96 kilometers.

3 0
2 years ago
(y^3+6y+3) and (y^2-6y-6)
Naily [24]
The answer is most definitely b.
3 0
2 years ago
Read 2 more answers
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