Answer:
t_a = 7 s
t_w = 5 s
Step-by-step explanation:
Given:
- The average speed in air v_a = 16 m/s
- The average speed in water v_w = 3 m/s
- The total distance D = 127 m
- The total time T = 12 s
Find:
How long did the stone fall in air and how long did it fall in the water?
Solution:
- Lets time taken by stone to drop through air as t_a = t_a.
- The time taken in water would be t_w = (12 - t_a)
- The total distance covered can be calculated as:
D = v_a*t_a+ v_w*(12 - t_a)
127 = 16*t_a + 3*(12 - t_a)
Simplify and solve for t:
91 = 16*t_a - 3t_a
13*t_a = 91
t_a = 7 s
t_w = 5 s
The average american eats 147 pounds of french fries in 18 years
So, what you want to do here is subtract the ice cream sold on the weekend from the ice cream that was sold during the rest of the week.
He sold 19 on Saturday and 27 on Sunday, so these numbers need to be subracted from your total for the week.
(Total Sold) - [(Amount sold Saturday) + (Amount sold Sunday)] = (Amount sold on weekdays)
153 - (19 + 27) = X
153 - 46 = X
107 = X
