Answer:
1.5 seconds
Step-by-step explanation:
h=-16t² – 16t+ 60
When the rock enter the water, the height is 0. ... h=0
0 = -16t² – 16t+ 60 = -4 * (4t² - 4t +15) = -4* (2t - 3) (2t +5)
2t-3=0 or 2t+5 = 0
t = 3/2 or t = -5/2 (time can't be negative)
t = 3/2 or 1.5
We must assume that all workmen work at the same rate, and keep it up forever.
More men ==> fewer days
so the proportion is: 30/25 = x/10
Cross-multiply the proportion:
300 = 25 x
Divide each side by 25 :
x = 300/25 = <u>12 men</u>
Answer:
x = 20
Step-by-step explanation:
I suspect that you might mean 'crimes' and 'police'. If that's the case,
then what we have here is a sentence that has not been proofread
for errors, and doesn't ask any question. I'm not going to worry about it.
