Respuesta :
Answer:
79%
Step-by-step explanation:
Most of today's student calculators have built-in statistical functions. I will use my old TI-83 Plus here:
normalcdf(20, 30, 25, 4)
The calculator returns 0.789.
Approximately 79% of the trees are between 20 and 30 years old
Answer:
68%.
Step-by-step explanation:
The mean is 25 and the standard deviation is 5. So 20 is one standard deviation below the mean and 30 is one standard deviation above the mean.
According to the Empirical Rule, 68% of the normal curve is between ±1 standard deviations. So the answer is 68%.