Answer:
Stratified Random sampling
Step-by-step explanation:
When a random observations are selected from a number of individual groups in a particular population, the type of sampling technique is called Stratified Random sampling. Stratified Random sampling begins with the partitioning or splitting or a population into subgroups. A number of random selection are then made from each of the subgroups to form a collection of larger samples. This is different from the simple random sampling technique which makes random selection directly from a larger sample or population without prior partitioning of the population. The different grades of students represents the individual stratum from which random selections are made.
It will take 40 minutes.
To solve, divide 60 by 3. 60 is how many minutes there are in a minute. 3 is how long it takes to paint 2/5 of the room. We do not need to use the number 2/5 in this situation. Now back to 60 divided by 3. The answer is 20 minutes. Now multiply 20 by 2 to get 2/3 of an hour. Therefore, it takes 40 minutes to paint 2/5 of a room.
Answer:

Step-by-step explanation:
Since there are a total of three buckets and only one can be chosen at a time, this would mean that the probability of a ball being placed in a bucket is 1/3. Since each ball has the same probability of being placed into any bucket regardless of the where the previous ball landed, it means that each ball has the same 1/3 probability of a bucket. In order to find the probability that all three land in the same bucket, we need to multiply this probability together for each one of the balls like so...

Finally, we see that the probability of all three balls landing in the same bucket is 
Answer:
6,000
Step-by-step explanation:
because it is a less amount of numbers to get to 6,000 than to get to 5,00
Take half of the coefficient on the x term