Question

SAT 数学题 帮忙解答下

if 3 more than x is 2 less than 9 , what is the value of x ？ if 4 bags of flour with an average (arithmetic mean)weight of 15pounds are put onto a shelf with 45-pound bags of flour , what is the average weight , in pounds of all 8 bags on the shelf ? a certain ice-cream parlor offers 6 different toppings for sundaes . how many combinations of 2 different toppings from those offered are possible ? if one of the positive factors of 40 is to be chosen at random , what is the probability that the chosen factor will not be a multiple of 10 ? the length of each side of an equilateral triangle will be tripled to create a second triangle . the area of the second triangle will be how many times the area of the original triangle ? when the positive ingeter x is divided by 5 , the remainder is 3 , what is the remainder when x+19 is divided by 5 ?

Answer 1

1.
x+3
=
9-2,
x=4
2.（4×15+45）/8=
13.125
pounds
3.
组合，C(6,2)=15
4.40的正因子有：1，2，4，5，8，10，20，40
因此，取到10的倍数的概率为3/8
5.
9倍，问的是等边三角形边长*3，则面积是原来的多少倍
6.
x/5=y+3,
so,x=5y+15
x+19=5y+34=5*(y+6)+4,so
the
remainder
is
4