Find square footage of his yard
assuming is is roughtly a rectangle
area of rectangle=length times width
length=20ft
width=12 ft
area=length times width=20 times 12= 240 square feet
how many packages?
1 pack times x is at least 240
1 pack times x>240
50 times x>240
divide both sides by 50
x>4.8
you can't buy 0.8 pack, so round up
5 packs needed
A=v1-v0/t
a*t=v1-v0
(a*t)+v0=v1
Saw A = 150 planks/30 seconds = 5 planks per second
Saw B = 130 planks/ 13 seconds = 10 planks per seconds
5 + 10 = 15 planks per second total
225 planks / 15 planks per second = 15 seconds
Answer: 15 seconds
To evaluate the probability that the lifespan will be between 1440 and 1465 hours will be given by:
P(1440<x<1465)
using the z-score formula we obtain:
z=(x-μ)/σ
where:
μ=1450
σ=8.5
hence
when x=1440
z=(1440-1450)/8.5
z=-1.18
P(z<-1.18)=0.1190
when x=1465
z=(1465-1450)/8.5
z=1.77
P(z<1.77)=0.9625
hence:
P(1440<x<1465)
=0.9625-0.1180
=0.8445
X=2.77 Explanation: log
(
3
x
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=
log
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21
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(Take log of both sides)
x
*
(
log
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3
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)
=
log
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21
)
x
=
log
(
21
)
log
(
3
)
x
=
2.77
