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

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 
The standard deviation is 
The population mean is 
The level of significance is 
The null hypothesis is 
The alternative hypothesis is
Generally the test statistics is mathematically represented as

=> 
=> 
Generally the p-value is mathematically represented as


From the z-table

=> 
=> 
From the obtained values we see that 
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

=> 
=> 
Phone card = $20
You need to minus 17.92 from 20 = $2.08
$2.08 / 0.13 = how many minutes
= 16
Answer:
Please find attached pdf
Step-by-step explanation:
The answer is 63 units, just add them up.