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qwelly [4]
3 years ago
9

The difference between a number and its square is 20. Find thenumbers.​

Mathematics
1 answer:
Elena L [17]3 years ago
4 0

Answer:

-4 or 5

Step-by-step explanation:

let number be x

x²-x=20

Rearrange

x²-x-20=0

(x+4)(x-5)=0

Separate

x+4=0, x-5=0

x=-4 or 5

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3 years ago
Assume that a fair six-sided die is rolled 13 times, and the roll is called a success if the result is in {1,2,3,4}. What is the
Deffense [45]

Answer:

The answer to the question is;

The probability that there are exactly 4 successes or exactly 4 failures in the 13 rolls is \frac{715}{8192}.

Step-by-step explanation:

The probability of success = 1/2 =

probability of failure  = 1/2

Since we have 4 success we then have 9 failures and the given probability can be solved as ₁₃C₄ × 1/2ⁿ×1/2¹³⁻ⁿ

Therefore  we have

₁₃C₄ × 1/2⁴×1/2⁹ =  715/8192

That is the probability that there are exactly 4 successes or exactly 4 failures in the 13 rolls = 715/8192.

5 0
3 years ago
An engineer designed a valve that will regulate water pressure on an automobile engine. The engineer designed the valve such tha
BartSMP [9]

Answer:

The decision rule is  

Reject the null hypothesis  

Step-by-step explanation:

From the question we are told that

    The population mean is \mu =  5.6  \ pounds/inch^2

     The  sample size is  n =  160

      The sample mean is  \=  x =  5.7  \  pounds/ inch^2

     The variance is \sigma ^2 =  0.25

       The level of significance is  \alpha   =  0.01

The null hypothesis is  H_o  :  \mu  =  5.6

The alternative hypothesis is H_a :  \mu > 5.6

Generally the standard deviation is mathematically represented as

           \sigma =  \sqrt{\sigma ^2 }

=>         \sigma =  \sqrt{0.25  }  

=>         \sigma =  0.5  

Generally the test statistics is mathematically represented as

        z =  \frac{\= x  - \mu }{ \frac{\sigma}{\sqrt{n}  } }

=>     z =  \frac{5.7  - 5.6  }{ \frac{0.5 }{\sqrt{ 160 }  } }  

=>     z =  2.53

From the z table  the area under the normal curve to the left corresponding to  2.53   is

        p-value =  P(Z >  2.53 ) =0.0057

From the value obtained we see that the p-value  < \alpha hence

The decision rule is  

Reject the null hypothesis  

The conclusion is  

There is sufficient evidence to conclude that the believe  that the valve performs above the specifications is true

 

5 0
3 years ago
A fish population in a lake decreases by 2% each year. What is the common ratio? (Write your answer as a decimal)
galina1969 [7]

Answer:

the common ratio is 0.98.

Step-by-step explanation:

A fish population in a lake decreases by 2% each year. We are asked to find the common ratio.

The decrease of population of fish 2% annually means the population becomes next year 100% - 2% = 98%

Therefore, the common ratio would be 98%. Upon converting 98 percent to a decimal we will get,

98% = \frac{98}{100}=0.98

Therefore, the common ratio or decay factor is 0.98.

8 0
3 years ago
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