A box contains four 10 nf and eight 100 nf capacitors. (a) what is the probability of obtaining at least two 10 nf capacitors if
2 answers:
there are 4 of the 10-nf and 8 of the 100-nf capacitors which is a total of 12 items.
the probability of drawing a 10-nf is: 4 out of 12 =
the probability of drawing a 100-nf is: 8 out of 12 =
(a) "at least two" means: 2 or 3 or 4
Probability of 2 (10's) and 2 (100's): x
x
x
=
Probability of 3 (10's) and 1 (100's): x
x
x
=
Probability of 4 (10's) and 0 (100's): x
x
x
=
2 or 3 or 4: +
+
=
(b) without replacement
Probability of 2 (10's) and 2 (100's): x
x
x
=
Probability of 3 (10's) and 1 (100's): x
x
x
=
Probability of 4 (10's) and 0 (100's): x
x
x
=
2 or 3 or 4: +
+
=
=
=
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Answer:
(B)
Step-by-step explanation:
Volume of fluid in the tank =1000 gallons
Initial Amount of Salt in the tank, A(0)= 30 pounds
Incoming brine solution of concentration 2 pounds of salt per gallon is pumped in at a rate of 4 gallons per minute.
Rate In=(concentration of salt in inflow)(input rate of brine)
The resulting mixture is pumped out at the same rate, therefore:
Rate Out =(concentration of salt in outflow)(output rate of brine)
Therefore:
The rate of change of amount of salt in the tank,