9 boys can paint a basketball court in 3 hours how long should 1 boy take working at the same rate
1 answer:
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Answer:
The reason why standard deviation of the entire class is greater than standard deviation of males and females considered separately, is that mean values for males and females are different from each other.
Step-by-step explanation:
The concept of mean is well represented by the following formula
mean = , where x1, x2, xn are the observations and N is the number of observations (population).
Standard deviation represents the distance between each observation and the mean of the population (all observations). The formula for this parameter is:
Standard deviation =√[((x1 - x)² + (x2-x)² + ....+ (xn-x)²)/N-1], where x1, x2,..., xn are the observations and x is the mean value.
In this case you have that each height registered is an observation and the number of observations represents the N value. As you can see if the mean for males is different from that of females their standard deviation will be different too. Usually males have heigths greater than that of females (1.77 vs 1.64, in USA for example), and heights inside each group will be more similar than between groups. Then, when you mix all observation there will be an increase in standard deviation, because you are mixing very different heigths
Answer and Explanation:
Gina wanted to swim at the pool. She is allowed to spend at most $30. The cost to swim in the pool is 3 dollars per hour plus a flat fee of $3. How many hours can Gina swim without going over her spending limit?
This problem can be represented by .
'x' would be the number of hours. "At most" means less than or equal to. So, the value of x would have to be less than or equal to 30.
So, Gina would have a maximum of 9 hours to swim in the pool.
Hope this helps.
