Angela#31.doc

你了解吗？牛顿问题英国伟大的科学家牛顿，曾经出过关于牛在牧场上吃草的题目，后来人们就把这类题目称为“牛顿问题”。 “牛顿问题”是这样的：“有一牧场，已知养牛27头，6天把草吃尽；养牛23头，9天把草吃尽。如果养牛21头，那么几天能把牧场上的草吃尽呢？并且牧场上的草是不断生长的。”这类题目的一般解法是：把一头牛一天所吃的牧草看作1，那么就有：（1）27头牛6天所吃的牧草为：276162 （2）23头牛9天所吃的牧草为：239207 （3）1天新长的草为：（207162）（96）15 （4）牧场上原有的草为：27615672 （5）每天新长的草足够15头牛吃，21头牛减去15头，剩下6头吃原牧场的草： 72（2115）72612（天） 现在我就了解了，谢谢您。吗？所以养21头牛，12天才能把牧场上的草吃尽。 1#1、计算（+）40= 20（+）= = =2、动脑筋Two numbers differ by 57. Their sum is 185. Find the numbers. Choices for the smaller number:54 64 74.2#1、计算2（）= （1）= 12（）= 6=2、动脑筋A bus went 318 km farther than a car. The car went one third as far as the bus. How far did each vehicle travel? Choices for the smaller number: 147 151 159 3#1、计算（）= （-）5= （）= 12（）=2、动脑筋one number is four times another number. The larger number is also 87 more than the smaller number. Find the numbers. Choices for the smaller number: 29 30 334#1、计算21（1+）= = （）= 12（6+）=2、动脑筋A clown weights 60 lb more than a trapeze artist. The trapeze artist weighs two thids as much as the clown. How much does each weigh? choices for the weight of the trapeze artist : 110 120 1255#1、计算 = 20 = =2、The U.S. Senate has 100 memebers, all Democrats or Republicans. Recently there were 12 more Democrats than Republicans. How many Senators from each political party were there at that time? Choices for the number of Republicans: 38 42 44 答案：1#1、31 3 1/12 1/62、if the smaller number is x, then x+x+57=185 x=642#1、5 0.9 16/5 2/32、if the car went x km, then 318+x=3x x=159 bus=318+159=4773#1、1/30 5.5 15/32 562、if the smaller number is x, then 4x=x+87 x=294#1、24 4/9 1/30 40/212、if the trapeze artist weights x lb, then 60+