解:(1)8.38×2
-2.75×7
-27.5%,
=(8.38-7.38)×2.75-27.5%,
=2.75-27.5%,
=2.475;
(2)4875÷75-253×32÷128,
=65-8096÷128,
=65-63.25,
=1.75;
(3)[254-56×(2
-1
+2.275)]÷65%,
=[254-56×(1.1+2.275)]÷65%,
=[254-56×3.375]÷65%,
=[254-189]÷65%,
=65÷65%,
=100;
(4)3.3÷(8.98-11.16×
+50%),
=3.3÷(8.98-7.44+50%),
=3.3÷(1.54+50%),
=3.3÷2.04,
=1
.
分析:(1)运用乘法分配律解答,
(2)(3)(4)根据四则运算计算方法,先算第二级运算,再算第一级运算,如果只含有同一级运算,按照从左到右顺序计算,有括号先算括号里面的解答.
点评:本题主要考查学生对于四则运算计算正确性的把握,在解答时有简便算法的要正确选择并应用.