A normal distribution has a mean of 312.00 and a standard deviation of 26.45. Which interval centered at the mean has a 68% probability of containing a random value drawn from the distribution?
A) [259.45, 364.55]
B) [270.45, 353.55]
C) [275.55, 348.45]
D) [285.55, 338.45]

Question

A normal distribution has a mean of 312.00 and a standard deviation of 26.45. Which interval centered at the mean has a 68% probability of containing a random value drawn from the distribution? 
A)    [259.45, 364.55]   
  B)    [270.45, 353.55]    
 C)    [275.55, 348.45]    
  D)    [285.55, 338.45]

holsteremission · Answer

If you're familiar with this rule: https://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule then you can guarantee a probability of $68\%$ by taking the interval of one standard deviation from the mean, or $[312-26.45,312+26.45]$.

autumn9913 · Answer

ok, thanks