Rebecca had 9/10 of a yard of ribbon. Then she gave 7/20 of a yard to a friend. How much does she have left? Explain your work
2 answers:
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Answer:
The number of people in one session that will spend within two standard deviations below the mean and one standard deviations above the mean time on Facespace is 394 people
Step-by-step explanation:
The given information are;
The mean time spent of Facespace, μ = 30 minutes
The standard deviation of the time spent daily, σ = 6 minutes
The number of people in one sitting, n = 2900 people
The time spent two standard deviations below the mean = 30 - 12 = 18 minutes
The time spent one standard deviations above the mean = 30 + 6 = 36 minutes
The Z-score values are;
Which gives;
For x = 30
For x = 18
From the z-score table, we have;
P(Z > -2) = 1 - 0.02275 = 0.97725
P(Z < 1) = 0.84134
Therefore, the probability P(-2 < Z < 1) = 0.97725 - 0.84134 = 0.13591
Given that there are 2900 are on in one sitting, the number of them that will lie within two standard deviations below the mean and one standard deviations above the mean = 2900 × 0.13591 = 394.139 which is approximately 394 people.