83.Give the English definition of standard deviation, 2 or 3 lines, there are 4 numbers, 9, 8, 7, 4, ask the standard deviation of these 4 numbers。ANS:根号下14
86.a jogger\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ s speed is 10 kelometer per hour, walker 6k/hour, 有个water foundation , if the jogger pass the water foundation after passing the walker, howmany minitutes does the jogger pass the water foundation before the walker.
88.Buy with the wholesale price, and sell as 10% discount as the list price, a 20% profit on the wholesale price, what is the list price.. Answer : 120
89.The range of 1/2 1/2^2 1/2^3 …. 1/2^10 A: 0—1/2 B: 2/3---1 C cannot remember , I forget the formual for this