1、Six trees are equally spaced along one side of a straight road. The distance from the first tree to the fourth is 60 feet. What is the distance in feet between the first and last trees?
2、At the end of 2005 Walter was half as old as his grandmother. The sum of the years in which they were born is 3860. How old will Walter be at the end of 2006?
3、The digits 1,2,3,4 and 9 are each used once to form the greatest possible even five-digit number. What is the digit in the tens place?
4、Every edge of a cube is colored either red or green. In order to have at least one red edge on every face of the cube, find the minimum number of edges that must be colored red.
5、When 31513 and 34369 are such divided by a certain 3-digit number, the remainders are equal. Find this remainder.
6、Three signal lights were set to flash every certain specified time. The first light flashes every 12 seconds, the second flashed every 30 seconds and the third one every 66 seconds, the signal lights flash simultaneously at 8:30 am. At what time will the signal lights next flash。
7、There are five balls with different weights.Everyball is less than(少于 ）100g。Now weigh（称）every two balls，and you willget113,116,110,117,118,114,112,121,120,and115g .What is the weight of the heaviest(最重的)ball?
