Answer:
512
Step-by-step explanation:
Answer:
The speed with which Ryan was rowing was 4 mph
Step-by-step explanation:
With a small boat, Ryan wants to row towards an island and come back at a speed of x mph and the island is 20 miles away from him.
Therefore, total 20 + 20 = 40 miles he rowed for 5 hours.
On the way to the island, there was a wind of 4 mph in the direction of his motion and on the way back also there was a wind of 4 mph in the direction of his motion.
So, in the total journey, he has a speed of (x + 4) mph.
Therefore,
⇒ x + 4 = 8
⇒ x = 4 mph.
Therefore, the speed with which Ryan was rowing was 4 mph. (Answer)
Answer:
Step-by-step explanation:
C
Here is all you need for b)
Answer:
The sampling method used is a stratified sampling method
Step-by-step explanation:
sampling is the selection of a predetermined representative subpopulation from a larger population, to estimate the characteristics of the whole population.
Stratified sampling: Here, the total population are divided into subcategories (strata) before sampling is done. The strata are formed based on some common characteristics. In our example, the times of the day (morning, afternoon and evening) has widely varying atmospheric conditions which will add biases to the measurement of air quality. For example, the air in the morning if compared to the afternoon in an industrial area may be purer because of minimal industrial activity, hence effective comparison will be made by stratification.