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Hypothesis Z, t, C.I

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Statistics

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Q1.
Ans
Pooled variance t test is Answer
Value of Combined Standard deviation is S= (n1*s1^2 + n2*s2^2 )/(n1+n2-2)
we use Test Statistic (t) = (X-Y)/Sqrt(S^2(1/n1+1/n2))
Q2.
Ans
Con$dence Interval
CI = x ± Z a/2 * (sd/ Sqrt(n))
Where,
x = Mean
sd = Standard Deviation
a = 1 - (Con$dence Level/100)
Za/2 = Z-table value
CI = Con$dence Interval
Mean(x)=42144
Standard deviation( sd )=3000
Sample Size(n)=10
Con$dence Interval = [ 42144 ± Z a/2 ( 3000/ Sqrt ( 10) ) ]
= [ 42144 - 1.96 * (948.6833) , 42144 + 1.96 * (948.6833) ]
= [ 40284.5807,44003.4193 ]
None of the above is Answer
Q3.
Ans
x = Mean
n = Sample Size
a = 1 - (Con$dence Level/100)
Za/2 = Z-table value
CI = Con$dence Interval
Mean(x)=54.4
Sample Size(n)=80
Sample proportion = x/n =0.68
Con$dence Interval = [ 0.68 ±Z a/2 ( Sqrt ( 0.68*0.32) /80) ]
= [ 0.68 - 1.96* Sqrt(0.0027) , 0.68 + 1.96* Sqrt(0.0027) ]
= [ 0.578,0.782] ~ [ 57.8% , 78.2% ]
58; 78 is Answer
Q4.

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CI = x ± Z a/2 * (sd/ Sqrt(n))
Where,
x = Mean
sd = Standard Deviation
a = 1 - (Con$dence Level/100)
Za/2 = Z-table value
CI = Con$dence Interval
Mean(x)=15.23
Standard deviation( sd )=1.65
Sample Size(n)=24379
Con$dence Interval = [ 15.23 ± Z a/2 ( 1.65/ Sqrt ( 24379) ) ]
= [ 15.23 - 1.96 * (0.0106) , 15.23 + 1.96 * (0.0106) ]
= [ 15.2093,15.2507 ]
15.21 ; 15.25 is Answer
Q5.
Under The Null Hypothesis H0:P=0.77
Under The Alternate Hypothesis H1: P!=0.77
Test Statistic
No. Of Success chances Observed (x)=219
Number of objects in a sample provided(n)=300
No. Of Success Rate ( P )= x/n = 0.73
Success Probability ( Po )=0.77
Failure Probability ( Qo) = 0.23
we use Test Statistic (Z) for Single Proportion = P-Po/Sqrt(PoQo/n)
Z cal=0.73-0.77/(Sqrt(0.1771)/300)
Z cal =-1.646 ~ - 1.65
-1.65 is Answer
Q6.
|Z cal | =1.646
Critical Value
The Value of |Z tab| at LOS 0.01% is 2.33
We got |Z cal| =1.646 & | Z tab | =2.33
Make Decision
Hence Value of |Z cal | < | Z tab | and Here we Accept Ho
P-Value: Two Tailed ( double the one tail ) - Ha : ( P != -1.64631 ) = 0.0997
We failed to reject the null Hypothesis
Q7.

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Q1. Ans Pooled variance t test is Answer Value of Combined Standard deviation is S= (n1*s1^2 + n2*s2^2 )/(n1+n2-2) we use Test Statistic (t) = (X-Y)/Sqrt(S^2(1/n1+1/n2)) Q2. Ans Confidence Interval CI = x ? Z a/2 * (sd/ Sqrt(n)) Where, x = Mean sd = Standard Deviation a = 1 - (Confidence Level/100) Za/2 = Z-table value CI = Confidence Interval Mean(x)=42144 Standard deviation( sd )=3000 Sample Size(n)=10 Confidence Interval = [ 42144 ? Z a/2 ( 3000/ Sqrt ( 10) ) ] = [ 42144 - 1.96 * (948.6833) , 42144 + 1.96 * (948.6833) ] = [ 40284.5807,44003.4193 ] None of the above is Answer Q3. Ans x = Mean n = Sample Size a = 1 - (Confidence Level/100) Za/2 = Z-table value CI = Confidence Interval Mean(x)=54.4 Sample Size(n)=80 Sample proportion = x/n =0.68 Confidence Interval = [ 0.68 ?Z a/2 ( Sqrt ( 0.68*0.32) /80) ] = [ 0.68 - 1.96* Sqrt(0.0027) , 0.68 + 1.96* Sqrt(0.0027) ] = [ 0.578,0.782] ~ [ 57.8% , 78.2% ] 58; 78 is Answer Q4. CI = x ? Z a/2 * (sd/ Sqrt(n)) Where, x = Mean sd = Standard Deviation a = 1 - (Confidence Level/100) Za/2 = Z-table value CI = Confidence Interval Mean(x)=15.23 Standard deviation( sd )=1.65 Sample Size(n)=24379 Confidence Interval = [ 15.23 ? Z a/2 ( 1.65/ Sqrt ( 24379) ) ] = [ 15.23 - 1.96 * (0.0106) , 15.23 + 1.96 * (0.0106) ] = [ 15.2093,15.2507 ] 15.21 ; 15.25 is Answer Q5. Under The Null Hypothesis H0:P=0.77 Under The Alternate Hypothesis H ...
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