Daisy measured the heights of 20 plants.
1 answer:
Answer:
- 30.5 cm
Step-by-step explanation:
<em>Refer to attached</em>
- Height of plants (h) >> Frequency >> Midpoint >> Frequency x midpoint
- 0 <h < 10 >> 1 >> 5 >> 5
- 10 <h < 20 >> 4 >> 15 >> 60
- 20 <h < 30 >> 7 >> 25 >> 175
- 30 <h < 40 >> 2 >> 35 >> 70
- 40 <h < 50 >> 3 >> 45 >> 135
- 50 <h < 60 >> 3 >> 55 >> 165
Sum of frequencies = 20
Sum of frequency x midpoint product = 610
<u>Mean height </u>
- 610/20 = 30.5 cm
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Answer: <u>Last option</u>
Step-by-step explanation:
The z-scores give us information about how many standard deviations from the mean the data are. This difference can be negative, if the data are n deviations to the left of the mean, or it can be positive if the data are n deviations to the right of the mean.
To calculate the Z scores, we calculate the difference between the value of the data and the mean and then divide this difference by the standard deviation.
so
.
Where x is the value of the data, μ is the mean and σ is the standard deviation
In this case :
μ = 12 $/h
= 2 $/h
We need to calculate the Z-scores for and
Then for :
.
Then for :
.
Therefore the answer is: