5) x̅ = 71.2, s = 2.4, n = 25
α = 0.05
Null and Alternative hypothesis:
Ho : µ = 69.5 (Claim)
H1 : µ ≠ 69.5
Test statistic:
t = (x̅- µ)/(s/√n) = (71.2 - 69.5)/(2.4/√25) =
3.5417
df = n-1 = 24
Critical value :
Two tailed critical value, t-crit = T.INV.2T(0.05, 24) =
2.064
Or using p-value :
Two tailed p-value = T.DIST.2T(ABS(3.5417), 24) = 0.0017
Decision:
p-value < α, Reject the null hypothesis.
Conclusion:
There is not enough evidence to support the claim that the mean height is 69.5 at 0.05 significance level.
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6). n = 400, x = 244
p̄ = x/n = 0.61
α = 0.05
Null and Alternative hypothesis:
Ho : p ≥ 0.70 (Claim)
H1 : p < 0.70
Test statistic:
z =(p̄ -p)/(√(p*(1-p)/n)) =
-3.9279
Critical value :
Left tailed critical value, z crit = NORM.S.INV(0.05) = -1.645
Or using p-value :
p-value = NORM.S.DIST(-3.9279, 1) = 0.0000
Decision:
p-value < α,
Reject the null hypothesis.
There is not enough evidence to support the claim that the proportion is at least 70% at 0.05 significance level.
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7).
| Category | Observed Frequency (O) | Expected Frequency (E) | (O-E)²/E |
| A | 25 | 210 * 0.14 = 29.4 | (25 - 29.4)²/29.4 = 0.6585 |
| B | 48 | 210 * 0.2 = 42 | (48 - 42)²/42 = 0.8571 |
| C | 63 | 210 * 0.3 = 63 | (63 - 63)²/63 = 0 |
| D | 43 | 210 * 0.2 = 42 | (43 - 42)²/42 = 0.0238 |
| F | 31 | 210 * 0.16 = 33.6 | (31 - 33.6)²/33.6 = 0.2012 |
| Total | 210 | 210 | 1.7406 |
Null and Alternative hypothesis:
Ho: p1 = 0.14, p2 = 0.20, p3 = 0.30, p4 = 0.20, p5 = 0.16 (Claim)
H1: Proportions are different.
Test statistic:
χ² = ∑ ((fo-fe)²/fe) =
1.7406
df = n-1 = 4
p-value:
p-value = CHISQ.DIST.RT(1.7406, 4) = 0.7833
Decision:
p-value > α, Do not reject the null hypothesis
There is enough evidence to support the teacher claim at 0.05 significance level.