Answer:
A. The distribution of sample means of the differences will be approximately normal if there are at least 30 years of data in the sample and/or if the population of differences in winning times for all years is normal.
Step-by-step explanation:
In other to perform a valid paired test, one of the conditions required is that, data for both groups must be approximately normal. To attain normality, the population distribution for the groups must be normal or based on the central limit theorem, the sample size must be large enough, usually n > 30. Hence, once either of the two conditions are met, the paired sample will be valid.
Answer:
x = 27/10 or x = 2.7
Step-by-step explanation:
Step 1: Get rid of the denominator.
LCD of 4 & 3: 12
Multiply both sides by 12.
12 ( 2x - 1 / 4 ) + 12 ( x / 3 ) = 12 (2)
Reduce the numbers.
3 ( 2x - 1) + 4x = 24
Step 2: Distribute.
6x - 3 + 4x = 24
Step 3: Collect like terms.
6x + 4x = 24 + 3 ( - 3, the sign change when moved to the other side)
10x = 27
Step 4: Solve for x.
Multiply both sides by 10.
10x / 10 = 27 / 10 (the 10 cancels out)
x = 27 / 10 or x = 2.7
Answer: x = 27 / 10 or x = 2.7
B is the most likely independent
Answer:
C. 2.0 < t < 2.5
Step-by-step explanation:
time = distance / speed
The circumference of the lake is given by ...
C = πd = 2π miles ≈ 6.28 miles
Then Johanna's time is ...
(6.28 mi)/(3 mi/h) ≈ 2.09 h
This time is in the interval (2, 2.5), so matches choice C.
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<em>Alternate solution</em>
If we take pi to be 3, then this boils down to ...
2×3/3 = 2 . . . hours
Pi is on the order of 5% more than 3, so her time will be on the order of 5% more than 2 hours, or just above 2, but not as great as 2.5 hours. This sort of estimating can get you to the correct answer without a calculator.
Not defective : 25 - 3 = 22
probability of not defective : 22/25
22/25 × 100% = 88%
