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Veronika [31]
3 years ago
6

In the Jefferson Middle School chorus, 60% of the members are girls. If there are 45 girls in chorus what is the total number of

chorus members?
Mathematics
1 answer:
PtichkaEL [24]3 years ago
4 0
There are 75 chorus members.
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Two buses leave a station at the same time and travel in opposite directions. One bus travels
natima [27]

Answer:

63 miles per hour

54 miles per hour

Step-by-step explanation:

Let the two buses be represented as bus A and bus B.

bus A and bus B leave a station at the same time and travel in opposite directions.

Let the speed of bus A be A miles per hour.

Let the speed of bus B be B miles per hour.

One bus travels 9 miles/hour slower than the other.

Let bus A be the faster bus.

This means that the speed of bus B is B = A - 9

If the two buses are 585 miles apart after 5hours, this means that after 5hours, the total distance travelled by bus A and bus B is 585 miles.

Distance travelled by bus A in 5 hours = speed × time = 5A

Distance travelled by bus B in 5 hours = speed × time = 5B

5A + 5B = 585 - - - - - -1

Substituting B = A - 9 in equation 1

5A + 5(A - 9) = 585

5A + 5A - 45 = 585

10A = 585 + 45 = 630

A = 630/10 = 63 miles per hour

B = A - 9 = 63 - 9 = 54 miles per hour

4 0
3 years ago
Which of these choices show a pair of equivalent expressions? A.7^5/7 and (√ 7)^5 B.6^7/2 and (√ 6)^7 C.(4√ 81)^7 and 81^7/4 D.5
OverLord2011 [107]
We will use the following law of indices (or 'index law') to check each pair of expression

x^{ \frac{m}{n}} = ( \sqrt[n]{x} )^{m}

With fractional power, the denominator is the root and the numerator is the power of the term. When the denominator is 2, we usually only write the normal square symbol (√). Denominator other than 2, we usually write the value of the root, for example, the cubic root ∛

Option A - Incorrect
7^{ \frac{5}{7}} should equal to ( \sqrt[7]{7} )^{5}

Option B - Correct
6^{ \frac{7}{2} } does equal to ( \sqrt{6}) ^{7}

Option C - Incorrect
4( \sqrt{81} )^{7} should equal to (4)( 81^{ \frac{7}{2} } )

Option D - Incorrect
5^{ \frac{2}{3} } should equal to ( \sqrt[3]{5} )^{2}
7 0
3 years ago
Read 2 more answers
Compute​ P(x) using the binomial probability formula. Then determine whether the normal distribution can be used to estimate thi
stich3 [128]

Answer:

The answers to the questions are;

A) P(X) where x = 12 is equal to 3.55 ×10⁻²

B) P(x) using the normal distribution is given by the probability distribution function and is equal to 3.453 ×10⁻²

C) The calculated probabilities of P(x=12) using the binomial probability formula and the probability distribution function differ by 9.7×10⁻⁴

D) The normal distribution be used to approximate this probability because     a. because np(1-p) %u2265 ⇒ np(1-p) ≥ 10

E) c. the value of fi represents the expected proportion of observation less than or equal to the ith data value.

Step-by-step explanation:

To solve the question, we note that

n = 58

p = 0.3

x = 12

Here we have n·p = 17.4 and n·q = 40.6 both ≥ 5 that is the normal distribution can be used to estimate the probability

A) We are to use the binomial probability formula to find P(X)

Where x = 12, we have P(12) = ₅₈C₁₂×0.3¹²×0.7⁴⁶

= 891794789340×0.000000531441×7.49×10⁻⁸ = 3.55 ×10⁻²

B) Using the standard distribution table we have

the z score for x = 12 given as z = \frac{x-\mu}{\sigma} = -1.55

From the normal distribution table, we have the probability that value is below 12 = .06057 while the normal probability distribution function which gives the probability of a number being 12 is given by

\frac{1}{\sigma\sqrt{2 \pi } } e^{\frac{-(x-\mu)^2}{2\sigma^2} }

where:

σ = Standard deviation = \sqrt{npq} = \sqrt{np(1-p)} = \sqrt{58*0.3*(1-0.3)} = 3.48999

μ = Sample mean = n·p = 58×0.3 =17.4

Therefore the probability density function is \frac{1}{3.49\sqrt{2 \pi } } e^{\frac{-(12-17.4)^2}{2*3.49^2} } = 3.453*10^{-2}

C)  The probabilities differ by 3.55 ×10⁻² -  3.453 ×10⁻² =  9.7×10⁻⁴

D) The normal distribution be used to approximate this probability because     n·p and n·p·(n-p) ≥ 5

E)   f_i represents the area under the curve towards left of the ith data observed in a normally distributed population.

Therefore, the value of fi represents the expected proportion of observation less than or equal to the ith data value  

5 0
2 years ago
IMPORTANT PLEASE HELP
Mademuasel [1]

Answer:

a + c = 80

a = 2c - 8

Step-by-step explanation:

Topic: Algebra

5 0
2 years ago
Pls anyone can help?
Luba_88 [7]
I think it’s 9/10 mile
3 0
3 years ago
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