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2 years ago

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In a fish tank, there are 24 goldfish, 2 angel fish, and 5 guppies. If a fish is selected at random, find the probability that i

t is a goldfish or an angel fish.
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1 answer:

horrorfan [7]2 years ago

3 0

There are 31 fish in total. There are 26 goldfish and angelfish. The probability is 26/31.

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Find the number a such that the line x = a bisects the area under the curve y = 1/x2 for 1 ≤ x ≤ 4. 8 5 (b) find the number b s

IceJOKER [234]

a. We're looking for $a$ such that

$\displaystyle\int_1^a\frac{\mathrm dx}{x^2}=\int_a^4\frac{\mathrm dx}{x^2}$

$-\dfrac1x\bigg|_{x=1}^{x=a}=-\dfrac1x\bigg|_{x=a}^{x=4}$

$1-\dfrac1a=\dfrac1a-\dfrac14$

$\dfrac54=\dfrac2a\implies\boxed{a=\dfrac85}$

b. Integrating with respect to $y$ will make things easier.

$y=\dfrac1{x^2}\implies x=\dfrac1{\sqrt y}$

(where we take the positive square root because we know $x>0$ )

Now we want to find $b$ such that

$\displaystyle\int_0^b\frac{\mathrm dy}{\sqrt y}=\int_b^1\frac{\mathrm dy}{\sqrt y}$

$2\sqrt y\bigg|_{y=0}^{y=b}=2\sqrt y\bigg|_{y=b}^{b=1}$

$2\sqrt b=2-2\sqrt b$

$4\sqrt b=2\implies\boxed{b=\dfrac14}$

3 0

2 years ago

On average, the number of customers who had items to return for refunds or exchanges at a certain retail store's service desk is

spayn [35]

Answer:

The probability that the service desk will have at least 100 customers with returns or exchanges on a randomly selected day is P=0.78.

Step-by-step explanation:

With the weekly average we can estimate the daily average for customers, assuming 7 days a week:

$M=756/7=108$

We can model this situation with a Poisson distribution, with parameter λ=108. But because the number of events is large, we use the normal aproximation:

$P(\lambda)\approx N(\lambda,\lambda)$

Then we can calculate the z value for x=100:

$z=\frac{x-\mu}{\sigma}=\frac{100-108}{\sqrt{108}}=\frac{-8}{10.4} =-0.77$

Now we calculate the probability of x>100 as:

$P(x>100)=P(z>-0.77)=0.78$

The probability that the service desk will have at least 100 customers with returns or exchanges on a randomly selected day is P=0.78.

5 0

2 years ago

Photon Lighting Company determines that the supply and demand functions for its most popular lamp are as follows: S(p) = 400 - 4

BlackZzzverrR [31]

S(p) = 400 - 4p + 0.00002p^4
D(p) = 2800 - 0.0012p^3

S(p) = D(p)
400 - 4p + 0.00002p^4 = 2800 - 0.0012p^3
0.00002p^4 + 0.0012p^3 - 4p - 2400 = 0
p = $96.24

6 0

2 years ago

Does the type of program people watch influence how much they eat? A total of 94 college students were randomly assigned to one

jolli1 [7]

Answer:

Television has been accused of helping people gain weight because it encourages a sedentary lifestyle. Television is like other entertaining activities that can get people to eat more, including reading, listening to the radio, and interacting with dinner mates.

8 0

2 years ago

Which products result in a difference of squares or a perfect square trinomial? Check all that apply.

tiny-mole [99]

Answer:

Option B) (7x+4)(7x+4) is correct

The product result in a perfect square trinomial is

$(7x+4)(7x+4)=49x^2+56x+14$

Step-by-step explanation:

$(7x+4)(7x+4)=(7x+4)^2$ ( using $(a+b)(a+b)=(a+b)^2$ )

$=(7x)^2+2(7x)(4)+4^2$ ( using $(a+b)^2=a^2+2ab+b^2$ )

$=7^2x^2+56x+16$

$=49x^2+56x+14$

Therefore $(7x+4)(7x+4)=49x^2+56x+14$

which is a perfect square trinomial

A trinomial is a perfect square trinomial if it can be factored into a binomial multiplied to itself. In a perfect square trinomial, two terms will be perfect squares.

Option B) (7x+4)(7x+4) is correct

The product result in a perfect square trinomial is

$(7x+4)(7x+4)=49x^2+56x+14$

6 0

2 years ago

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