Answer:
a) 72.25sec
b) 6.25secs
c) after 10.5secs and 2 secs
Step-by-step explanation:
Given the height reached by the rocket expressed as;
s(t)= -4t^2 + 50t - 84
At maximum height, the velocity of the rocket is zero i.e ds/dt = 0
ds/dt = -8t + 50
0 = -8t + 50
8t = 50
t = 50/8
t = 6.25secs
Hence it will reach the maximum height after 6.25secs
To get the maximum height, you will substitute t - 6.25s into the given expression
s(t)= -4t^2 + 50t - 84
s(6.25) = -4(6.25)^2 + 50(6.25) - 84
s(6.25) = -156.25 + 312.5 - 84
s(6.25) = 72.25feet
Hence the maximum height reached by the rocket is 72.25feet
The rocket will reach the ground when s(t) = 0
Substitute into the expression
s(t)= -4t^2 + 50t - 84
0 = -4t^2 + 50t - 84
4t^2 - 50t + 84 = 0
2t^2 - 25t + 42 = 0
2t^2 - 4t - 21t + 42 = 0
2t(t-2)-21(t-2) = 0
(2t - 21) (t - 2) = 0
2t - 21 = 0 and t - 2 = 0
2t = 21 and t = 2
t = 10.5 and 2
Hence the time the rocket will reach the ground are after 10.5secs and 2 secs
Answer: 2 / 15
Step-by-step explanation:
3 red / 10 total
4 white / 9 total
3/10 * 4/9 = 12/90 = 2/15
Answer:
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The answer is 4 have a great day!
Part 1: 2×2×3×3×3=108 (c)
Part 2: 10×9×26×25×4=234000 (c)
Part 3: 10×9×8×7×6×5×4×3×2×1÷(3×2×1)=604800 (d)
Part 4: 11C4=11×10×9×8÷(4×3×2×1)=330 (a)
Part 5: ⅕=20% (c)
Part 6: 100-2.9=97.1 (d)
