Basic Applied Statistics 200
Solutions to Midterm 2
-
- 24+2(4)=32
- z=(17-24)/4=-1.75
- (iv) because z is between -1.96 and -1.645
-
- (iii) (large enough n ensures Central Limit Theorem applies
- (ii) (pop greater than 10n ensures dependence doesn't undermine
formula for sd)
- PROPORTION has mean p=.2 and sd square root of p(1-p)/n = .05
- z=(.23-.20)/.05=.6
- (i) because z is not unusual
-
- mean of sample means is population mean 2, s.d. of sample means is
population s.d. over square root of sample size, or .2
- (iii) As we take larger samples, the shape becomes closer to normal.
However, 25 is a medium-sized sample, and the distribution is clearly
right-skewed, so sample mean will still have right skewness.
- (iii) probabilities based on the normal curve aren't valid for skewed
distributions
-
- (ii) (Small n yields smaller test statistic and larger p-value.)
- (i) (The null hypothesis is that the vaccine makes no difference.)
-
- (ii)
- (vii)
-
- (ii)
- (i) (p-value is only about half of the cut-off alpha=.05)
- .052 (twice the size)
- (iii) because the two-sided p-value is borderline
-
- (ii) (referring to t sketch, p-value>.05, so we can't reject Ho)
- (iii) (because standardized sample mean does not follow t distribution
when sample is small and non-normal)
- (iii) (because sample is not representative)
- (i) (referring to z sketch because sample is large; p-value is just
under .025, so we reject Ho
- (iii) (it's the furthest ABOVE 600)
- (i) (it's the furthest AWAY FROM 600)
-
- .63 plus or minus 2(.04)= (.55, .71)
- (i) because the multiplier would be less than 2
- (iii) because .75 is outside the interval
- (ii)
- (i)
[ Home
| Calendar
| Assignments
| Handouts
]
|