1. It's time to burn incense.
There are two incense sticks, which burn for one hour. How to burn incense to determine the time of fifteen minutes?
Tip: the problem is not to burn it in fifteen minutes, but to determine the time of fifteen minutes.
2. Calculate the length of the rope and the depth of the well
I don't know how deep the well is, but I don't know how long the rope is.
Fold the rope into three folds and hang one end at the bottom of the well. When the lower end of the rope reaches the bottom hole, the upper end is lower than the wellhead 1 ft.
If the rope is folded in two, when the lower end reaches the bottom of the well, the upper end is 6 feet higher.
Do you know how deep this well is? How long is the rope?
3. Mathematical calculation of lighting candles
Two candles, one thin and the other thick.
The thin candle is 30 cm long and can be lit for 3 hours.
The thick candle is 20 cm long and can be lit for 5 hours.
Light these two candles at the same time. A few hours later, the two candles are the same length.
(answer form: XX hours XX minutes)
Drinks 4.40 yuan
Xiao Li has 40 yuan. He wants to buy drinks with them. The boss told him that 2 yuan could buy one bottle of drinks, and four bottles could be exchanged for one.
Then, how many bottles of drinks can Xiao Li buy
5. Calculate the ages of four sons
A family has four sons. Multiply the ages of these four sons to get 15.
So, how old are the four sons in this family?
6. Divide 48 jellies into 4 parts.
Xiaohong's mother bought 48 jellies. Xiaohong's mother said to Xiaohong, if you can divide these jellies into four parts, let the first part add 3, the second part subtract 3, the third part multiply 3 and the fourth part divide 3, and the results are the same, then you can eat these jellies.
Xiaohong thought for a long time and finally came up with this problem. Do you know how to divide the smart ones?
Answer:
1. Light two incense sticks at the same time and one incense stick at both ends at the same time, and the burning time is half an hour; The other one has only one end on. The first incense is burned and the other end is lit, which is 15 minutes.
2. Well 15 ft, rope 42 ft.
3. 1 hour 40 minutes, 30÷3= 10 (cm); 20÷5=4 (cm); (30-20) ÷ (10-4) = 1 0 ÷ 6 = 5/3 (hour) =1hour for 40 minutes.
Buy 20 bottles of drinks with 40 yuan money first, and you will get 20 bottles. If you exchange four bottles for one drink, you will get five bottles, then five bottles, and then 1 drink, so you will get 20+5+ 1=26 bottles.
5. The decomposition factor of15, 15 = 5 * 3 * 1 5 =15 *1*, so these four sons may have one.
6. The four copies are 12, 6, 27 and 3 respectively. Suppose these four jellies are all X, then the first one is X+3, the second one is X3, the third one is 3X, and the fourth one is X/3, and the total is 48, so X=9. So we can know how much each one is.