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3 years ago

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The ratio of girls to boys in fifth grade at Travis Elementary is 2 to 3. If there are a total of 90 students in fifth grade, ho

w many girls attend Travis Elementary?

2 answers:

Cerrena [4.2K]3 years ago

7 0

Answer:

45

Step-by-step explanation:

Vera_Pavlovna [14]3 years ago

4 0

Answer:

The ratio of girls to boys in the fifth grade is 36 to 54

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3 years ago

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3 years ago

Assume that X is a binomial random variable with n = 27 and p = 0.90. Calculate the following probabilities. (Do not round inter

Yuki888 [10]

Answer:

a) $P(X=26) = 27C26 (0.9)^{26} (1-0.9)^{27-26}= 0.1744$

b) $P(X=25) = 27C25 (0.9)^{25} (1-0.9)^{27-25}= 0.2520$

c) $P(X=25) = 27C25 (0.9)^{25} (1-0.9)^{27-25}= 0.2520$

$P(X=26) = 27C26 (0.9)^{26} (1-0.9)^{27-26}= 0.1744$

$P(X=27) = 27C27 (0.9)^{27} (1-0.9)^{27-27}= 0.0582$

And addind the values we got:

$P(X\geq 25)= P(X=25)+P(X=26)+P(X=27)=0.2520+0.1744+0.0582=0.4846$

Step-by-step explanation:

Previous concepts

The binomial distribution is a "DISCRETE probability distribution that summarizes the probability that a value will take one of two independent values under a given set of parameters. The assumptions for the binomial distribution are that there is only one outcome for each trial, each trial has the same probability of success, and each trial is mutually exclusive, or independent of each other".

Solution to the problem

Let X the random variable of interest, on this case we now that:

$X \sim Binom(n=27, p=0.9)$

The probability mass function for the Binomial distribution is given as:

$P(X)=(nCx)(p)^x (1-p)^{n-x}$

Where (nCx) means combinatory and it's given by this formula:

$nCx=\frac{n!}{(n-x)! x!}$

Part a

We want this probability:

$P(X=26)$

And we can use the probability mass function and we got:

$P(X=26) = 27C26 (0.9)^{26} (1-0.9)^{27-26}= 0.1744$

Part b

We want this probability:

$P(X=25)$

And we can use the probability mass function and we got:

$P(X=25) = 27C25 (0.9)^{25} (1-0.9)^{27-25}= 0.2520$

Part c

We want this probability:

$P(X\geq 25)= P(X=25)+P(X=26)+P(X=27)$

And we can use the probability mass function and we got:

$P(X=25) = 27C25 (0.9)^{25} (1-0.9)^{27-25}= 0.2520$

$P(X=26) = 27C26 (0.9)^{26} (1-0.9)^{27-26}= 0.1744$

$P(X=27) = 27C27 (0.9)^{27} (1-0.9)^{27-27}= 0.0582$

And addind the values we got:

$P(X\geq 25)= P(X=25)+P(X=26)+P(X=27)=0.2520+0.1744+0.0582=0.4846$

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3 years ago

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Answer:

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2)ofcourse, when u plug -2 it makes it 0, f (-2)=0

3)the remainder being constant implies it is divisible by (x-1), 2x^2 (x-1)+4 (x-1), so ax^2=2x^2, a=2

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4 years ago