Respuesta :
Answer:
b. between 195 and 275 dollars.
Step-by-step explanation:
The standard deviation rule, or the 68-95-99.7 rule, states that, for a normally distributed random variable X:
68% of the measures are within 1 standard deviation of the mean
95% of the measures are within 2 standard deviations of the mean.
99.7% of the measures are within 3 standard deviations of the mean.
In this problem, we have that:
Mean 235, standard deviation 20.
According to the Standard Deviation Rule, in a semester, most (95%) of the students spent on textbooks:
Between 235 - 2*20 = 195 dollars and 235 + 2*20 = 275 dollars.
So the correct answer is:
b. between 195 and 275 dollars.
Answer:b. between 195 and 275 dollars
Step-by-step explanation:
The Standard Deviation Rule states that for a normal distribution, nearly all of the data will fall within three standard deviations of the mean . The empirical rule is further illustrated below
68% of data falls within the first standard deviation from the mean.
95% fall within two standard deviations.
99.7% fall within three standard deviations.
From the information given, the mean is $235 and the standard deviation is $20.
95% of the amount spent by students on text books would fall within two standard deviations.
2 standard deviations = 2 × 20 = 40
235 - 40 = 195
235 + 40 = 275
Therefore, the amount spent is between between 195 and 275 dollars.
