Answer: Exponential decay model:
y
=
x
(
1
−
r
)
t
, half life of tablet is about
2
hours and after
t
=
3
hours , remaining drug on patient's system is
42.875
mg.
Step-by-step explanation: Initial drug
x
=
125
mg ; rate of decay
r
=
30
100
=
0.3
gm/hour
Exponential model:
y
=
x
(
1
−
r
)
t
=
125
(
1
−
0.3
)
t
=
125
⋅
0.7
t
Half life:
y
=
125
2
=
62.5
mg
∴
62.5
=
125
⋅
0.7
t
or
0.7
t
=
1
2
. Taking logarithm on both sides we get ,
t
log
(
0.7
)
=
log
(
0.5
)
∴
t
=
log
(
0.5
)
log
(
0.7
)
≈
1.94
(
2
d
p
)
hour
The half life of tablet is about
2
hours.
After
t
=
3
hours , remaining drug on patient's system is
y
=
125
⋅
0.7
t
=
125
⋅
0.7
3
=
42.875
mg [Ans]
Answer: The required system of equations representing the given situation is

Step-by-step explanation: Given that Sam needs to make a long-distance call from a pay phone.
We are to write a system to represent the situation.
Let x represent the number of minutes Sam talked on the phone and y represents the total amount that he paid for the call.
According to the given information,
with prepaid phone card, Sam will be charged $1.00 to connect and $0.50 per minute.
So, the equation representing this situation is

Also, if Sam places a collect call with the operator he will be charged $3.00 to connect and $0.25 per minute.
So, the equation representing this situation is

Thus, the required system of equations representing the given situation is

Answer:
B
Step-by-step explanation:
The volume (V) of a rectangular prism is calculated as
V = length × width × height
Calculate the volume of each prism
Q → V = 8 × 4 × 5 = 60 ft³
R → V = 6 × 7 × 12 = 504 ft³
S → V = 4 × 10 × 12 = 480 ft³
T → V = 2 × 13 × 5 = 130 ft³
Prism R has the greatest volume → B
Answer:
x=6
Step-by-step explanation:
Step 1: Subtract 4x from both sides.
5x−3−4x=4x+3−4x
x−3=3
Step 2: Add 3 to both sides.
x−3+3=3+3
x=6