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Rudik [331]
1 year ago
9

Dan is watching The Birds in his backyard. Of the birds he watches, 9. Of them,or 45%, are sparrows. How many birds are in his b

ackyard?
Mathematics
1 answer:
ra1l [238]1 year ago
5 0

If 9 of the sparrows is 45% of the birds in the backyard, 9/x = 45/100.

Cross multiply to get 9 * 100 = 45x; simplified is 900 = 45x or 20.

This means that there are 20 birds in the backyard. You can check this by dividing 9/20 which equals 45%

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At summer camp the ratio of boys to girls was 7:2 If there were 21 boys how many girls were there?
Alenkinab [10]
Ratio:\\7:2\\\\
7x-number\ of\ boys\\2x-number\ of\ boys\\\\
7x=21\ \ \ |:7\\
x=3\\\\
2x=2*3=6\\
Number\ of\ girls\ is\ equal\ to\ 6.
3 0
1 year ago
Let X represent the amount of time until the next student will arrive in the library parking lot at the university. If we know t
Ber [7]

Answer:

The probability that it will take more than 10 minutes for the next student to arrive at the library parking lot is 0.0821.

Step-by-step explanation:

The random variable <em>X</em> is defined as the amount of time until the next student will arrive in the library parking lot at the university.

The random variable <em>X</em> follows an Exponential distribution with mean, <em>μ</em> = 4 minutes.

The probability density function of <em>X</em> is:

f_{X}(x)=\lambda e^{\lambda x};\ x\geq 0, \lambda >0

The parameter of the exponential distribution is:

\lambda=\frac{1}{\mu}=\frac{1}{4}=0.25

Compute the value of P (X > 10) as follows:

P(X>10)=\int\limits^{\infty}_{10}{0.25e^{-0.25x}}\, dx

                 =0.25\times \int\limits^{\infty}_{10}{e^{-0.25x}}\, dx\\=0.25\times |\frac{e^{0.25x}}{-0.25}|^{\infty}_{10}\\=(e^{-0.25\times \infty})-(e^{-0.25\times 10})\\=0.0821

Thus, the probability that it will take more than 10 minutes for the next student to arrive at the library parking lot is 0.0821.

3 0
1 year ago
In quadrilateral ABDC, AB ∥ CD. Which additional piece of information is needed to determine that ABDC is a parallelogram? AB ≅
siniylev [52]

For any quadrilateral to be a parallelogram

i) either both the pairs of opposite sides must be equal

ii) Both the pairs of opposite sides must be parallel

iii) Opposite pairs of angles must be equal

iv) Diagonals must bisect each other.

v) A pair of opposite sides must be parallel and equal

Here we are already given that AB || CD

So either we should be given that AD || BC

or we must be given that AB = CD

Here it is given AB = CD as an option.

So Option A) or the first option is the right answer that AB ≅CD is needed to prove ABCD is a parallelogram.


7 0
2 years ago
Read 2 more answers
When dividing with polynomials, the goal is to determine how many times the dividend divides evenly into the?
kkurt [141]
Whether dividing constant terms or polynomials, we always have definitive terms when it comes to division. Suppose we say, 10x divided by 2. The dividend is the 10x and the divisor is the 2. In other words, the dividend is the number to be divided by the divisor, to obtain the answer called the quotient.

When dividing polynomials, your main goal is to be able to divide the dividend evenly into the <em>divisor</em>. For example, we divide x²+2x+1 by x+1. The first thing you're going to focus is, what term will completely divide the first term of the polynomial? That would be x. Why? Because when you multiply x with x+1, the product is x²+x. When you subtract this from the polynomial, the x² will cancel out. All you have to do is subtract x from 2x, yielding x. Then, you carry down the last term of the equation: +1. You do the steps again. The term that will completely divide x+1 by x+1 is 1. When you subtract the two, you will come up with zero. That means there is no remainder. The polynomial is divisible by the divisor. 
                          x + 1
                        ------------------------------------
                  x+1| x²+2x+1
                        - x²+x
                         ----------------------
                                 x +1
                               - x + 
                             ------------
                                    0
5 0
1 year ago
The time needed to travel a certain distance varies inversely with the rate of speed. If it takes 8 hours to travel a certain di
katen-ka-za [31]
I believe it would be 4.8 hours
5 0
1 year ago
Read 2 more answers
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