Four students went to plant trees. The tree planted by the first student is half of the total number of trees planted by other students, the tree planted by the second student is a quarter of the total number of trees planted by other students, the tree planted by the third student is a fifth of the total number of trees planted by other students, and the fourth student just gets 15 trees. Ask four students a * * *, how many trees have they planted?
The fruit shop brought two kinds of fruits, apples and pears. The number of kilograms of apples is 3/4 of that of pears, and 2/5 apples are 45 kilograms more than pears. How many kilograms of apples and pears did you bring?
It is known that it takes 30 days for Party A to complete a project, 45 days for Party C and 90 days for Party C.. Now, Party A, Party B and Party C will cooperate to complete the project. During the work, A had a rest for 2 days and B had a rest for 3 days. C didn't rest, and finally finished the project. Q: When was the project completed from the beginning?
1.
When water is added for the first time, the wine remains unchanged, taking wine as the unit. Namely:
5÷ (100/30-100/40) = 6 (kg) This is the wine in front.
Ask for 30% liquor: 6 ÷ 30% = 20 (kg)
Find the water of 30% solution: 20-6 = 14 (kg).
Ask questions again, add wine, the water is constant, take the actual water quantity, and 50% of the wine is regarded as one unit. Namely:
14 ÷ 50% = 28 (kg) Question: 28-20 = 8 (kg)
A: Add 8 kilograms of alcohol.
2.
Convert Unit 1 and unify Unit 1 into Unit 1, with a total of 14 people. Namely:
The first student accounts for the total: two plus one third1one third.
The second student accounts for the total: four plus one fifth 1/5.
The third student accounts for the total: five plus one sixth 1/6.
Then the fourth student accounts for three tenths of the total:1-1/3-1/5-1/6 = 3/10.
15 ÷ 3/ 10 = 50 (tree)
Four students planted 50 trees together.
3.
Establish mathematical models and compare them.
3/4 apples = 5/ 12 pears
Apple: pear = 5/ 12: 3/4
Apple: pear = 5: 9
Take the number of copies in Billie as a specific amount and find each copy.
5× 2/5 = 29×112 = 3/4. Please note that these have no units.
45 ÷ (2-3/4) = 36 (kg) per share.
Apple: 36× 5 = 180 (kg) pear: 36× 9 = 324 (kg)
A: We shipped180kg of apples and 324kg of pears.
4.
The total work is regarded as a unit.
A work efficiency 1/30 B work efficiency 1/45 C work efficiency 1/90.
How many days did it take: (1-/kloc-0 /×1/30-3×1/90) ÷ (1/30+1/90)
My idea is: count the first three days, assuming that the rest days are all in the first three days, then in the first three days, A works 1 day, B doesn't work, and C works for three days. If all these are removed, it means that three people cooperate (without rest), and the number of days of cooperation plus the first three days is a * * *.
Also note that after working for 17 days, I have been working until 18 days.
A: This project was completed in 18 days from the beginning.