Answer:
(C) 2√15
Step-by-step explanation:
Recognize that all the triangles are right triangles, so are similar to each other. In these similar triangles, the ratio of the short side to the long side is the same for all.
... CB/CA = CT/CB
... CB² = CA·CT = 10·6 = 60 . . . . . . . . . . multiply by CA·CB; substitute values
... CB = √60 = 2√15 . . . . . . . take the square root; simplify
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<em>Comment on this solution</em>
The altitude to the hypotenuse of a right triangle (CB in this case) divides the hypotenuse into lengths such that the altitude is their geometric mean. That is ...
... CB = √(AC·CT) . . . . as above
This is true for any right triangle — another fact of geometry to put in your list of geometry facts.
Answer:
(0, -4)
Step-by-step explanation:
Answer:
a = 5
Step-by-step explanation:
a/4 = 15/12
We can use cross products to solve
a* 12 = 4*15
12a = 60
Divide each side by 12
12a/12 = 60/12
a =5
Answer:
x = - 2, x = 0
Step-by-step explanation:
- 3x² - 6x ← factor out - 3x from each term
= - 3x(x + 2)
To solve equate to zero
- 3x(x + 2) = 0
Equate each factor to zero and solve for x
- 3x = 0 ⇒ x = 0
x + 2 = 0 ⇒ x = - 2
Answer:Given:
P(A)=1/400
P(B|A)=9/10
P(B|~A)=1/10
By the law of complements,
P(~A)=1-P(A)=399/400
By the law of total probability,
P(B)=P(B|A)*P(A)+P(B|A)*P(~A)
=(9/10)*(1/400)+(1/10)*(399/400)
=51/500
Note: get used to working in fraction when doing probability.
(a) Find P(A|B):
By Baye's Theorem,
P(A|B)
=P(B|A)*P(A)/P(B)
=(9/10)*(1/400)/(51/500)
=3/136
(b) Find P(~A|~B)
We know that
P(~A)=1-P(A)=399/400
P(~B)=1-P(B)=133/136
P(A∩B)
=P(B|A)*P(A) [def. of cond. prob.]
=9/10*(1/400)
=9/4000
P(A∪B)
=P(A)+P(B)-P(A∩B)
=1/400+51/500-9/4000
=409/4000
P(~A|~B)
=P(~A∩~B)/P(~B)
=P(~A∪B)/P(~B)
=(1-P(A∪B)/(1-P(B)) [ law of complements ]
=(3591/4000) ÷ (449/500)
=3591/3592
The results can be easily verified using a contingency table for a random sample of 4000 persons (assuming outcomes correspond exactly to probability):
===....B...~B...TOT
..A . 9 . . 1 . . 10
.~A .399 .3591 . 3990
Tot .408 .3592 . 4000
So P(A|B)=9/408=3/136
P(~A|~B)=3591/3592
As before.
Step-by-step explanation: its were the answer is
