95. Set A has n integers. Arithmetic mean is m. standard deviation is R. Set B has all the elements of A and x. if standard deviation of B is r , is r < R? (1) x = m (2) m <= x <= m+R
请帮我确认这题答案?? D or A??
108. one man drives from west to east. He saw the mile marker of 88. the number 88 has the property, like 484 and 57475, when you reverse the number, it appears to be the same. Then that man drives the other 2 hours at the speed of 70 mile per hour. How many numbers that he would see will possess that property. 72*2+88=144+88=232 看88到232之间有多少个这类数(不包括88):99,101,111,121,131,141,151,161,171,181,191,202,212,222。共14个。 KEY:14 这题到底在说甚么啊?? 为什么88和232不算??
149. 点(2,3) 离y轴多远 根号(3-0)^2=3 KEY:3 这题不是很明显点(2,3)是距离2吗?? 怎么解释呢?? |