Question

Математика 6 класс №1574 Сплав массой 360 г состоит из меди и цинка. Отношение массы меди к массе цинка равно 3:2. Найдите массу меди и массу цинка в сплаве. №1575 Из посаженных 300 семян лука взошли 195. Каков процент всхожести семян лука?

Answer 1

№1574
частей 3+2=5, 360/5=72 - 1 часть
72*3=216 г меди
72*2=144 г цинка
№1575
пропорция:
300 - 100%
195 - х%,
300х=19500, х=65%

Answer 2

1574
3+2=5
360/5=72г - 1 часть
72*3=216г - масса меди
72*2=144г - масса цинка
Ответ  216г и 144г
1575
195/300*100=65% - всхожесть семян

Answer 3

№1574: Let's solve the problem step by step. We know that the alloy has a total mass of 360 grams and the ratio of the mass of copper (Cu) to the mass of zinc (Zn) is 3:2.

Step 1: Set up the equations Let's assume the mass of copper in the alloy is x grams, and the mass of zinc is y grams.

So, we have two equations based on the information given:

1. x + y = 360 (The total mass of the alloy is 360 grams)
2. x/y = 3/2 (The ratio of the mass of copper to the mass of zinc is 3:2)

Step 2: Solve the equations From equation 2, we can rewrite it as x = (3/2) * y and then substitute this value into equation 1:

(3/2) * y + y = 360 (5/2) * y = 360 y = 360 * 2 / 5 y = 144 grams

Now, we can find the mass of copper (x) using equation 2: x = (3/2) * y x = (3/2) * 144 x = 216 grams

So, the mass of copper in the alloy is 216 grams, and the mass of zinc is 144 grams.

№1575: To find the percentage germination of onion seeds, we can use the following formula:

Percentage germination = (Number of seeds germinated / Total number of seeds planted) * 100

Given that 300 seeds were planted, and 195 of them germinated, we can calculate the percentage germination:

Percentage germination = (195 / 300) * 100 Percentage germination = 0.65 * 100 Percentage germination = 65%

So, the percentage germination of onion seeds is 65%.