Answer:
D.) 4x + y
Step-by-step explanation:
3x + x + y
Add 3
x and x
.
4
x + y
Answer: 
Step-by-step explanation:
Using the data given in the exercise, we can draw the diagram attached, where "h" is the height of the building reached by the top of the ladder.
Notice that there are two similar triangles.
So, you can set up the following proportion:

Finally, in order to calculate the height on the building reached by the top of the ladder, you must solve for "h".
Therefore, the value of "h" is :

Answer:
Step-by-step explanation:
Let the number of blue marbles be x
The number of green marbles = 3x - 2
Total marbles= 18
x + 3x -2 = 18
4x - 2 = 18
4x = 18+2
4x = 20
x =20/4
x =5
The number of blue marbles = 5
The number of green marbles = 3*5 - 2 = 15 -2 = 13
Answer:
a) The probability that at least 3 months elapse before the first earthquake of destructive magnitude occurs is P=0.7788
b) The probability that at least 7 months elapsed before the first earthquake of destructive magnitude occurs knowing that 3 months have already elapsed is P=0.7165
Step-by-step explanation:
Tha most appropiate distribution to model the probability of this events is the exponential distribution.
The cumulative distribution function of the exponential distribution is given by:

The destructive earthquakes happen in average once a year. This can be expressed by the parameter λ=1/year.
We can express the probability of having a 3 month period (t=3/12=0.25) without destructive earthquakes as:

Applying the memory-less property of the exponential distribution, in which the past events don't affect the future probabilities, the probability of having at least 7 months (t=0.58) elapsed before the first earthquake given that 3 months have already elapsed, is the same as the probability of having 4 months elapsed before an earthquake.

