Answer:
a) P(t>3)=0.30
b) P(t>10|t>9)=0.67
Step-by-step explanation:
We have a repair time modeled as an exponentially random variable, with mean 1/0.4=2.5 hours.
The parameter λ of the exponential distribution is the inverse of the mean, so its λ=0.4 h^-1.
The probabity that a repair time exceeds k hours can be written as:
(a) the probability that a repair time exceeds 3 hours?
(b) the conditional probability that a repair takes at least 10 hours, given that it takes more than 9 hours?
The exponential distribution has a memoryless property, in which the probabilities of future events are not dependant of past events.
In this case, the conditional probability that a repair takes at least 10 hours, given that it takes more than 9 hours is equal to the probability that a repair takes at least (10-9)=1 hour.
Answer:
Width: 10.5 feet
Length: 31.5 feet
Step-by-step explanation:
Let x represent width of the concrete slab.
We have been given that the length of a concrete slab is three more than three times the width. So length of the slab would be 
.
We are also told that the area of slab is 330 square feet. We can represent this information in an equation as:
Now, we will take square root of both sides.
Therefore, the width of slab is approximately 10.5 feet.
The length of the slab would be 
.
Therefore, the length of slab is approximately 31.5 feet.
Answer:
7.99+2(1.09)+3(2.75)+x =25
Step-by-step explanation:
what's given are the prices of the canvas, brushes, and bottles of pain. 7.99 represents the one canvas Anna is buying, 2(1.09) represents the 2 brushes, and 3(2.75) represents the bottle of paints. Now what's left is x and x represents the amount of money left on the gift card. The gift card is $25 in total so that's why at the end of the equation it equals to $25.
3.2 divided by 0.4 would be 8
