Answer:
-16
Step-by-step explanation:
Answer:
decreasing at 390 miles per hour
Step-by-step explanation:
Airplane A's distance in miles to the airport can be written as ...
a = 30 -250t . . . . . where t is in hours
Likewise, airplane B's distance to the airport can be written as ...
b = 40 -300t
The distance (d) between the airplanes can be found using the Pythagorean theorem:
d^2 = a^2 + b^2
Differentiating with respect to time, we have ...
2d·d' = 2a·a' +2b·b'
d' = (a·a' +b·b')/d
__
To find a numerical value of this, we need to find the values of its variables at t=0.
a = 30 -250·0 = 30
a' = -250
b = 40 -300·0 = 40
b' = -300
d = √(a²+b²) = √(900+1600) = 50
Then ...
d' = (30(-250) +40(-300))/50 = -19500/50 = -390
The distance between the airplanes is decreasing at 390 miles per hour.
Answer:
a-bi
Step-by-step explanation:
If a quadratic equation lx^2+mx+n=0 has one imaginary root as a+bi then the other root is the conjugate of a+bi = a-bi
Because we have l, m and n are real numbers and they are the coefficients.
Sum of roots = a+bi + second root = -m/l
When -m/l is real because the ratio of two real numbers, left side also has to be real.
Since bi is one imaginary term already there other root should have -bi in it so that the sum becomes real.
i.e. other root will be of the form c-bi for some real c.
Now product of roots = (a+bi)(c-bi) = n/l
Since right side is real, left side also must be real.
i.e.imaginary part =0
bi(a-c) =0
Or a =c
i.e. other root c-bi = a-bi
Hence proved.
Answer:
a) 0.2416
b) 0.4172
c) 0.0253
Step-by-step explanation:
Since the result of the test should be independent of the time , then the that the test number of times that test proves correct is independent of the days the river is correct .
denoting event a A=the test proves correct and B=the river is polluted
a) the test indicates pollution when
- the river is polluted and the test is correct
- the river is not polluted and the test fails
then
P(test indicates pollution)= P(A)*P(B)+ (1-P(A))*(1-P(B)) = 0.12*0.84+0.88*0.16 = 0.2416
b) according to Bayes
P(A∩B)= P(A/B)*P(B) → P(A/B)=P(A∩B)/P(B)
then
P(pollution exists/test indicates pollution)=P(A∩B)/P(B) = 0.84*0.12 / 0.2416 = 0.4172
c) since
P(test indicates no pollution)= P(A)*(1-P(B))+ (1-P(A))*P(B) = 0.84*0.88+ 0.16*0.12 = 0.7584
the rate of false positives is
P(river is polluted/test indicates no pollution) = 0.12*0.16 / 0.7584 = 0.0253