The lifetimes of all the batteries produced by a certain company in a year have a distribution that is symmetric about the mean m. If the distribution has a standard deviation of d, what percent of the distribution is greater than m+d?
(1) 68 percent of the distribution lies in the interval from m-d to m+d, inclusive.
(2) 16 percent of the distribution is less than m-d.
(1) 68 percent of the distribution lies in the interval from m-d to m+d, inclusive.
(2) 16 percent of the distribution is less than m-d.
The question stem tells you that Distribution is symmetrical around mean m so 50% above m and 50% below.
St-1 68% is between m-d and m+d, this tells you that on the side which is higher 34% is between m and m+d so, remaining 16% has to be above m+d. SUFFICIENT
St-2 tells you that 16% is below m-d, so on the other side 16% will be above m+d. SUFFICIENT as well.
This is actually a normal distribution, where 68% is between 1 Standard deviation (SD), 96% between 2 SD and rest within 3 SD.
St-1 68% is between m-d and m+d, this tells you that on the side which is higher 34% is between m and m+d so, remaining 16% has to be above m+d. SUFFICIENT
St-2 tells you that 16% is below m-d, so on the other side 16% will be above m+d. SUFFICIENT as well.
This is actually a normal distribution, where 68% is between 1 Standard deviation (SD), 96% between 2 SD and rest within 3 SD.
Ans :D
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