设10个数:195.5,196.5,197.5,198.5,199.5,200,200.5,201,201.5,202.5的平均数为A,则10A=________.
网友回答
1993
解析分析:经观察,这10个数都与200相近,把每个数减200所得的差,分别记作-4.5,-3.5,-2.5,-1.5,-0.5,0,+0.5,+1,+1.5,+2.5,上述这10个差数的平均数为-0.7,A=199.3,所以10A=1993.
解答:∵195.5,196.5,197.5,198.5,199.5,200,200.5,201,201.5,202.5与200分别相差
-4.5,-3.5,-2.5,-1.5,-0.5,0,+0.5,+1,+1.5,+2.5,
∵[(-4.5)+(-3.5)+(-2.5)+(-1.5)+(-0.5)+0+0.5+1+1.5+2.5]÷10=-0.7,
∴A=200-0.7=199.3,
则10A=1993.
故