Under certain circumstance a rumor spreads according to the equation p ( t ) = 1 1 + a e − k t where p ( t ) is the proportion of the population that has heard the rumor at time t and a and k are positive constants. [In Section 9.4 we will see that this is a reasonable equation for p ( t ).] (a) Find lim t→∞ p ( t ). (b) Find the rate of spread of the rumor. (c) Graph p for the case a= 10, k = 0.5 with 1 measured in hours. Use the graph to estimate how long it will take for 80% of the population to hear the rumor.
Under certain circumstance a rumor spreads according to the equation p ( t ) = 1 1 + a e − k t where p ( t ) is the proportion of the population that has heard the rumor at time t and a and k are positive constants. [In Section 9.4 we will see that this is a reasonable equation for p ( t ).] (a) Find lim t→∞ p ( t ). (b) Find the rate of spread of the rumor. (c) Graph p for the case a= 10, k = 0.5 with 1 measured in hours. Use the graph to estimate how long it will take for 80% of the population to hear the rumor.
Solution Summary: The author explains how to find the function's limit, and the rate of spread of the rumor.
Under certain circumstance a rumor spreads according to the equation
p
(
t
)
=
1
1
+
a
e
−
k
t
where p(t) is the proportion of the population that has heard the rumor at time t and a and k are positive constants. [In Section 9.4 we will see that this is a reasonable equation for p(t).]
(a) Find limt→∞ p(t).
(b) Find the rate of spread of the rumor.
(c) Graph p for the case a= 10, k = 0.5 with 1 measured in hours. Use the graph to estimate how long it will take for 80% of the population to hear the rumor.
The bracket BCD is hinged at C and attached to a control cable at B. Let F₁ = 275 N and F2 = 275 N.
F1
B
a=0.18 m
C
A
0.4 m
-0.4 m-
0.24 m
Determine the reaction at C.
The reaction at C
N Z
F2
D
The correct answer is C,i know that we need to use stokes theorem and parametrize the equations then write the equation F with respect to the curve but i cant seem to find a way to do it, the integral should be from 0 to 2pi but i might be wrongcould you show me the steps to get to 18pi
A 10-ft boom is acted upon by the 810-lb force as shown in the figure.
D
6 ft
6 ft
E
B
7 ft
C
6 ft
4 ft
W
Determine the tension in each cable and the reaction at the ball-and-socket joint at A.
The tension in cable BD is
lb.
The tension in cable BE is
lb.
The reaction at A is (
lb) i +
Ib) j. (Include a minus sign if necessary.)
Chapter 3 Solutions
Bundle: Calculus: Early Transcendentals, 8th + WebAssign Printed Access Card for Stewart's Calculus: Early Transcendentals, 8th Edition, Multi-Term
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