At the construction site, cement, yellow sand and stones are mixed into a kind of concrete according to the ratio of 2:3:5. Now there are 5 tons of yellow sand on the ground, all of which are used up How many tons of cement and stones are needed? What's the formula

At the construction site, cement, yellow sand and stones are mixed into a kind of concrete according to the ratio of 2:3:5. Now there are 5 tons of yellow sand on the ground, all of which are used up How many tons of cement and stones are needed? What's the formula

Cement = 5 × 2 △ 3 = 10 / 3T
Stone = 5 × 5 △ 3 = 25 / 3T
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The school organized 280 students from grade 6 to go on a spring outing. Each student was given a bottle of mineral water, and the unit price was 2 yuan
How many options do you have? Which one do you think is better?
1. Buy 280 bottles of water, a total of 560 yuan
2. Buy 23 small boxes and 4 bottles, a total of 2 * 12 * 0.9 * 23 + 2 * 4 = 504.8 yuan
3. Buy 14 large boxes, a total of 14 * 20 * 2 * 0.8 = 448 yuan
In fact, there are other plans, but choosing those plans is tantamount to having trouble with yourself. You can choose your own
If a1 + A2 = 1, A3 + A4 = 9, then A4 + A5 equals ()
A. 27b. 27 or - 27c. 81D. 81 or - 81
When q = - 3, a1 + A2 = a1 + 3A1 = 4A1 = 1, so A1 = 14, A4 + A5 = 14 × (Q3 + Q4) = 27; similarly, when q = 3, A4 + A5 = - 27, so choose B
Four cars transport 920 bags of cement in five days. How many bags of cement does each car transport per day?
920 ﹣ 5 ﹣ 4 = 184 ﹣ 4 = 46 (bags); answer: on average, each car carries 46 bags of cement every day
There are 5 cases of mineral water, each case has 24 bottles, each bottle is 2 yuan. How much does it cost to buy these mineral water? Can you use different methods to check?
How to check
5 * 24 * 2 = 240 yuan
Checking calculation: 1) there are 24 * 5 = 120 bottles,
240 yuan, then 240 / 120 = 2 (yuan / bottle)
2) 2 yuan per bottle, 24 bottles per case, 240 yuan, 240 / 2 / 24 = 5 (cases)
If the equal ratio sequence satisfies an > 0, common ratio q = 2, A1 * A2 * A3 *. A30 = 2 ^ 30, then A1 * A4 * A7 *. A28 =?
Why is the answer 1?
It is easy to calculate A1 = 2 ^ (- 29)
The common ratio of the new sequence is 8
That's good
A batch of cement needs to be transported to the construction site. 240 trucks need to be transported every day in 40 days. Now it takes 16 days. How many trucks should be transported every day?
Let x car every day, 240 &; 40 = 16 &; X
240x40 divided by 16
A tourist team rents a car for travel, and each person should pay 40 yuan. Later, eight people came, and each person should pay 35 yuan. How much is the fare together?
Suppose there are x people in all
40x=35(x+8)
The solution is x = 56
The total fare is 40 * 56 = 2240 yuan
It's a very simple math problem,
A tourist team rents a car for travel, and each person should pay 40 yuan. How many people are there
Let's say it's x people
A total of 40x + 35 * 8
=40x + 280 yuan
Suppose there were x persons, then:
40x=(x+8)*35
40x=35x+280
5x=280
x=56
The total fare = 56 * 40 = 2240 yuan.
35 × 8 △ 5 × 40 = 2240 (person)
It is known that in the equal ratio sequence {an} composed of positive numbers, the common ratio q = 2, A1 · A2 · A3 · ·A30 = 45th power of 2, then A1 · A4 · A7 ·a28=?
Note: 1,3,30 in a1a2a3 are subscripts
Then A1 · A4 · A7 ·a28=？ The same is true
Let the first item be a
a*(aq)*(aq^2)*...*(aq^29)=2^45
a^30*q^(1+2+3+...+29)=2^45
a^30*q^(435)=2^45
a^30*2^435=2^45
a^30=2^(45-435)
a^30=2^(-390)
(a^10)^3=[2^(-130)]^3
a^10=2^(-130)
(28-1)÷3+1=10
a1*a4*a7*...*a^28………… (10 items in total)
=a^10*q^(3+6+...+27)
=a^10*q^30
=a^10*2^30
=2^(-130)*2^30
=2^(-130+30)
=2^(-100)
Use 4 cars to transport 30 tons of cement a day, ask 8 cars how many days to transport 120 tons of cement?
Suppose four cars are one share, eight cars are two
The daily transportation volume of 8 vehicles: 30 × (8 △ 4) = 60 (tons)
Then the number of days required for 8 vehicles of 120 tons is: 120 △ 60 = 2 (days)