青蛙跳井问题（Frog jump problem）.docVIP

青蛙跳井问题（Frog jump problem） 1. there is a frog, dropped 100 meters in the wells, he every day to jump 6 meters, and 4 meters down, ask him a few days to jump out. 2. words have a 10 meter wells, a frog at night and during the day to climb 3 meters, a few meters, ask for days to climb The problem on the stairs There is such a topic: if each on a flight of stairs in 1 minutes, then from one layer to four layers of how many minutes? If your answer is 4 minutes, then you are wrong. The correct answer is 3 minutes. Why is 3 minutes instead of 4 minutes? The original from the floor to the four floor, as long as three floors, stairs instead of four. Here are some similar problems. In 1 cases the tailor has a 16 m long woolen, cut every 2 meters, the first few days cut out the last paragraph? If the analysis is 2 meters without woolen, woolen 4 meters shear; if, on the first day of the last paragraph can be cut to 4 meters, there are 2 to 2 meters, only 1 days; if the cloth is 6 meters, the first day to cut 2 meters, 4 meters left, second days will be able to cut the last a section of 6 meters, there are 3 to 2 meters, only 2 days; if the cloth is 8 meters, the first day to cut 2 meters, 6 meters left, second days and then cut 2 meters, 4 meters left, so third days to cut out the last paragraph, 8 meters in 4 to 2 meters, with 3 days,...... We can find the rules from the days: the number of 2 meters of less than 1.. Therefore, as long as 16 meters in some 2 meters, the problem will be solved. Solution: contains the number of 2 meters 16 meters: 16 / 2=8 (a) Cut out the last paragraph with the number of days: 8-1=7 (day) Answer: seventh days can be cut out the last paragraph. 2 cases of a wood in 24 seconds was cut into 4 sections, cut into 5 pieces with the same speed, how many seconds? You can find the rules from the total number: the number of cut cut 1. less so in 24 seconds cut 4, only cut 3 times, so we can calculate the cut once the time, because the cut into 5 pieces w