(1)65+45=110,
45×0.61+65×0.3=46.95;
(2)(90+92+98+105+110)÷5=99;
(3)小明家这5个月的月平均用电量呈上升趋势;这5个月每月电费呈下降趋势;
(4)设平时段x度,谷时用(500﹣x)度,
则0.61x+0.3(500﹣x)=243
0.61x++150﹣0.3x=243
0.31x=93
x=300,
500﹣x=200
答:平时段300度,谷时用200度
(1)65+45=110,
45×0.61+65×0.3=46.95;
(2)(90+92+98+105+110)÷5=99;
(3)小明家这5个月的月平均用电量呈上升趋势;这5个月每月电费呈下降趋势;
(4)设平时段x度,谷时用(500﹣x)度,
则0.61x+0.3(500﹣x)=243
0.61x++150﹣0.3x=243
0.31x=93
x=300,
500﹣x=200
答:平时段300度,谷时用200度