I recently fell in love with Jiuxin chocolate and ate three boxes in just one month. Today, I pestered my mother again and said, "Mom, I'm running out of alcoholic chocolate. Buy me two more boxes online. " "Yes, yes, yes," my mother made a condition. "But this time, you have to pick it yourself. If you can't find something cheap and good, you won't buy it. " "good!" I am full of promises and eager to try.
After some comparison, the three schemes entered the final screening. All three schemes include my favorite rum chocolate and vodka chocolate. News 1: Two boxes of bulk chocolate are to be sold in 39 yuan, with monthly sales of 1875 and 3999 respectively. News No.2: Two boxes of chocolates tied together in 68 yuan, with monthly sales of 16 12. The third news: Two out of three, 55 yuan, with a monthly sales volume of 29. Seeing with eyes, I couldn't see which scheme was the best, so I decided to use pen to calculate. Scheme 1 needs 39+39=78 yuan, and the monthly sales volume is 1875+3999=5874 boxes. The price ratio of the three schemes is 78: 65: 55, and the third scheme is slightly better. Monthly sales ratio: 5874: 16 12: 29, and the first scheme is the most. "It's the same two boxes. Scheme 1 costs 78-65= 13 yuan more than Scheme 2. Although the monthly sales volume of scheme 1 is 5874- 16 12=4262 (boxes) more than that of scheme 2, the monthly sales volume is 1665438+. I gave my own inference. Mom nodded, and the first plan was eliminated.
Looking at the second and third schemes, I am puzzled. 65-55= 10 (yuan), the difference is 10 yuan! I can't bear to throw away 10 yuan. In addition, a little less monthly sales does not necessarily mean that chocolate is inferior. Suddenly I saw a small line in the lower right corner of the picture of the second scheme: fake one loses three. I was very excited, so I quickly ordered the third plan, haha! The fox's tail can't be hidden, and the seller didn't dare to write this sentence. A closer look shows that there is no evaluation at all in Scheme III, but there are more than 900 in Scheme II. Now, number three has been eliminated. At this moment, mother said, "Well done, you are very smart, and you will receive two boxes of alcoholic chocolates soon!" " ""yes! " I jumped three feet for joy.
Three days later, the chocolate arrived. I can't wait to open the vodka chocolate. One bite at a time. "Cough, cough, it hurts me!" I coughed and shouted, but I didn't expect the smell of wine to be so strong! Mom heard the news and came: "It seems that you finally have the authentic wine-heart chocolate." I smiled and then opened the rum chocolate. This time I learned my lesson and tasted it slowly. The smell of wine almost made me drunk. I tasted the alcoholic chocolate I bought with my brain and was flattered. I spent the whole afternoon immersed in the mellow beauty of wine chocolate. Do you want to eat authentic alcoholic chocolate? Please come to my house!
2, the fifth grade composition mathematics thesis 2
When I came home from school, I smiled and dragged my mother into the kitchen, trying to "get" some "benefits"-going to the bookstore to buy books. "Ding-ding!" Before mom could say "yes", the phone rang. It turned out that the daily questions came. My mother looked at them, rolled her eyes and smiled: "You do the right questions independently, and I'll take you to buy books at once!" I also attached delicious food ~ "I thought about it: if it is still the previous question type, then I will definitely do it!" "There is an attractive" gift ",so I agreed.
Mom wrote down the question, and I was puzzled when I read it. This is a problem that I have never touched: there are 36 students reading books in the school reading room, of which girls account for 4/9, and then several girls come. At this time, the number of girls accounted for 919 of the total number. How many girls came to read later?
I just stared at the topic, my mind went blank, and it took me a while to come to my senses. I quickly asked my mother who was stealing music, "Mom, is there any hint?" Give me a back door ~ "She cleared her throat and pretended to be serious and asked me to think about it myself. I pursed my lips, lowered my head and looked at the problem again.
Five minutes later, I didn't have a clue, muttering "36 people, 4/9 girls, and later it became 9/ 19."
Ten minutes later, I was thinking about my book, but I still didn't think carefully. I feel something, but I'm still not clear enough. I reluctantly pulled my hair and asked for help again. I took my mother's hand and shook it again and again. I said politely, "Dear mother, beautiful mother, please help me and give me a hint?" My mother was really shaken, thought for a moment and said, "Oh, I really can't stand it. I'll tell you what. Think about it, girls have changed, who hasn't? "
Who hasn't changed? Haha, it's really a word to wake up the dreamer. Girls have changed, the total number has changed, and the number of boys has not changed. Then never change-let's start with boys!
It is known that "there are 36 students reading books in the reading room, of which 4/9 are girls". The original total number of people is regarded as the unit "1", with an average of 9, among which 4 are girls, so boys account for 5/9 of the original total number, and boys account for 36×5/9=20 (people). According to "a few girls came later, and the number of girls accounted for 9/ 19 of the total number", the current total number is regarded as "1", with an average score of 19, and girls are 9 of them, so boys have 10. Although the total number has changed, the number of boys remains the same. It can be seen that "20 boys" corresponds to "10 boys". So just use 20÷ 10=2 (people) to calculate the current number of people. Now there are two people and nine girls in one copy. Now there are 2×9= 18 girls, while there were 36×4/9= 16 girls before. Use 18- 16=2 (person) to get rid of the girls coming from behind.
It's a pity that I didn't find such a simple invariant hidden in it! I secretly blamed myself, but my mother said happily, "Not bad, but it makes sense!" " I'd better take you to buy books! It would be better if you don't dial next time! "Say, touched my head.
Start with invariants! Haha, through this question, I not only learned new ideas and methods to solve the problem, but also got what I wanted, got a lot of love books and ate a "Pizza Hut".
There is mathematics everywhere in life, which contains many mysteries of knowledge, waiting for us to explore and discover constantly.