(Простите, пожалуйста, мой английский. Русский не мой родной язык. Надеюсь, у вас есть способ перевести это решение. Если нет, возможно, прилагаемое изображение объяснит достаточно.)
Use the shell method. Each shell has a height of 3 - 3/4 <em>y</em> ², radius <em>y</em>, and thickness ∆<em>y</em>, thus contributing an area of 2<em>π</em> <em>y</em> (3 - 3/4 <em>y</em> ²). The total volume of the solid is going to be the sum of infinitely many such shells with 0 ≤ <em>y</em> ≤ 2, thus given by the integral

Or use the disk method. (In the attachment, assume the height is very small.) Each disk has a radius of √(4/3 <em>x</em>), thus contributing an area of <em>π</em> (√(4/3 <em>x</em>))² = 4<em>π</em>/3 <em>x</em>. The total volume of the solid is the sum of infinitely many such disks with 0 ≤ <em>x</em> ≤ 3, or by the integral

Using either method, the volume is 6<em>π</em> ≈ 18,85. I do not know why your textbook gives a solution of 90,43. Perhaps I've misunderstood what it is you're supposed to calculate? On the other hand, textbooks are known to have typographical errors from time to time...
The problem above is an example of conditional probability. From the name itself, it gives you a condition that a certain event has already happen, or is sure to happen. In this case, the probability would be 100% or 1. The condition says that the probability is 100% if the packages are more than 3. Since, 4 is considered to be more than 3, then the probability is 100%.
Answer: 4 days (I think)
Step-by-step explanation:
One cat = 150*2 = 300g
Two cats = 600g
600*2 = 1200 (this is the total amount of food they both eat in a day)
5kg = 5000g
1200g/5000g = 4.17
The bag will last 4 days.
To be the best you can be at whatever you're practicing. Just because you can't be perfect doesn't mean you can't be very good at it.