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qwelly [4]
3 years ago
10

Malena has taken four tests so far. Her scores are 92%,80%,88%,93%. What score does she need to get on the fifth test to raise h

er average grade to 90%?
Mathematics
1 answer:
hammer [34]3 years ago
4 0
To calculate the average you add up all the scores and divide by the number of scores (5)
add all the current test scores and allow X to be the unknown score:
92+80+88+93+X: or 353 + X

set up equation:

(353+X)
______    =  90
    5

Multiply both side of the equation by 5 to clear the fraction resulting in:

353+X=450

Subtract 353 from both sides of the equation:

x = 97

So the test score needed to get a 90 average is 97.
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Which algebraic expression represents “ six less than a number “
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Researchers have noted a decline in cognitive functioning as people age (Bartus, 1990). However, the results from other research
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Complete Question

The complete question is shown on the first uploaded image

Answer:

a

Yes the researcher can  conclude that the supplement has a significant effect on cognitive skill

b

d =  0.5778

c

The result of this hypothesis test shows that there is sufficient evidence to  that the supplement had significant effect.The measure of effect size is  large due to the large value of Cohen's d (0.5778 > 0.30 )

Step-by-step explanation:

From the question we are told that

  The sample size is  n=16

    The sample mean is  M  =  50.2

    The standard deviation is \sigma  = 9

    The  population mean is  \mu =  45

     The level of significance is  \alpha =  0.05

The null hypothesis is H_o  \mu =45

The alternative hypothesis is H_a  \mu \ne 45

Generally the test statistics is mathematically represented as

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

=>       z =  \frac{50.2 - 45}{\frac{9}{\sqrt{16} } }

=>       z =  2.31

Generally the p-value is mathematically represented as

     p-value  =  2 *  P(Z >  z )

      p-value  =  2 *  P(Z >  2.31 )

From the z-table  

      P(Z >  2.31 ) = 0.010444

=>     p-value  =  2 *  0.010444

=>     p-value  =  0.021

From the obtained values we see that p-value <  0.05

 Decision Rule

 Reject the null hypothesis

Conclusion

There is sufficient evidence to conclude that the supplement has a significant effect on the cognitive skill of elderly adults

Generally the Cohen's d for this study is mathematically represented as

    d =  \frac{M  -  \mu}{\sigma }

=>  d =  \frac{50.2 -45}{9 }

=>  d =  0.5778

3 0
4 years ago
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