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xz_007 [3.2K]
3 years ago
10

Researchers recorded that a certain bacteria population declined from 450,000 to 900 in 30 hours at this rate of decay how many

bacteria will there be in 13 hours
Mathematics
1 answer:
worty [1.4K]3 years ago
5 0

Answer:

30,455

Step-by-step explanation:

Exponential decay

y = a(1 - b)^x

y = final amount

a = initial amount

b = rate of decay

x = time

We are looking for the rate of decay, b.

900 = 450000(1 - b)^30

1 = 500(1 - b)^30

(1 - b)^30 = 0.002

1 - b = 0.002^(1/30)

1 - b = 0.81289

b = 0.1871

The equation for our case is

y = 450000(1 - 0.1871)^x

We are looking for the amount in 13 hours, so x = 13.

y = 450000(1 - 0.1871)^13

y = 30,455

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Twelve percent of U.S. residents are in their forties. Consider a group of nine U.S. residents selected at random. Find the prob
miskamm [114]

Answer:

The probability is 28 % ( approx )

Step-by-step explanation:

Since, there are only two possible outcomes in every trails ( residents are in their forties or not ),

So, this is a binomial distribution,

Binomial distribution formula,

Probability of success in x trials,

P(x)=^nC_x p^x q^{n-x}

Where, ^nC_x=\frac{n!}{x!(n-x)!}

p and q are probability of success and failure respectively and n is the total number of trials.

Let X be the event of resident who are in his or her forties.

Here, p = 12% = 0.12,

⇒ q = 1 - p = 1 - 0.12 = 0.88,

n = 9,

Hence, the probability that two or three of the people in the group are in their forties = P(X=2) + P(X=3)

^9C_2 (0.12)^2 (0.88)^{9-2}+^9C_3 (0.12)^3 (0.88)^{9-3}

=36(0.12)^2 (0.88)^7+84(0.12)^3 (0.88)^6

=0.279266611163

\approx 0.28

=28\%

7 0
3 years ago
What does rate of change mean
jeka94

Answer:

A rate of change is a rate that describes how one quantity changes in relation to another quantity.

8 0
4 years ago
A ceramics store manufactures and sells coffee mugs. The revenue r(x) from the sale of x coffee mugs is given by r(x)-6.5x. Supp
KonstantinChe [14]

Answer:

Step-by-step explanation:

The revenue r(x) from the sale of x coffee mugs is given by

r(x) = 6.5x

the function for the cost of manufacturing x coffee mugs is c(x)= 0.75x + 1850.

Profit = Revenue - cost

P(x) = r(x) - c(x)

P(x) = 6.5x - (0.75x + 1850)

P(x) = 6.5x - 0.75x - 1850

P(x) = 5.75x - 1850

A) profit when x = 500 is

P = 5.75 × 500 - 1850

P = 2875 - 1850

P = 1025

profit when x = 1000 is

P = 5.75 × 1000 - 1850

P = 5750 - 1850

P = 3900

profit when x = 5000 is

P = 5.75 × 5000 - 1850

P = 28750 - 1850

P = 26900

B) The profit function would be

P(x) = r(x) - c(x)

P(x) = 5.75x - 1850

3 0
3 years ago
before school began mrs. weeks bought a total of 86 balls us the information below to help you write a numerical expression​
STALIN [3.7K]

For this case we have that the total of the balls is 86. We know there are 8 footballs then:

Basketball: Two more than twice the number of footballs are basketballs, that is:

2 + 2 (8) = 2 + 16 = 18

There are 18 Basketballs.

Baseballs: Four less than 5 times the number of footballs are baseballs, that is:

5 (8) -4 = 40-4 = 36

There are 36 Baseballs.

Softballs: Six more than half of baseballs are softballs. That is to say:

6+ \frac {36} {2} = 6 + 18 = 24

There are 24 Softballs

If we add we must get 86.

8 + 18 + 36 + 24 = 86

ANswer:

There are 8 Footballs

There are 18 Basketballs.

There are 36 Baseballs.

There are 24 Softballs

3 0
3 years ago
PICTURE ATTACHMENT IS BELOW
alina1380 [7]

Answer:

10% = 1/10

20% = 1/5

100% = 3/3

75% = 3/4

Step-by-step explanation:

5 0
3 years ago
Read 2 more answers
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