Answer
According to newton law of cooling

and

now At Ta = 100
T₀ = 10 °C
T₁ = 12° C

10 = C + 100
C = -90
now,



at time equal to t
T(t) = 70



t = 48.88 s
hence, after 48.88 s the temperature of the body will be 70°C
b) time taken to reach 98°C



t = 390 s
hence, after 390 s the temperature of the body will be 98°C
Answer:
180
Step-by-step explanation:
The speed upstream is the difference between the boat speed and the current speed. It is (12 mi)/(4 h) = 3 mph.
The speed downstream is the sum of the boat speed and the current speed. It is (32 mph)/(4 h) = 8 mph.
The speed of the boat is the average of these: (3 + 8)/2 = 5.5 mph.
The speed of the current is that less the difference: 5.5 - 3 = 2.5 mph.
_____
<u>Check</u>
Boat + Current = 5.5 + 2.5 = 8 mph
Boat - Current = 5.5 - 2.5 = 3 mph
Answer:
D
Step-by-step explanation:
Answer:
$76.50
Step-by-step explanation:
17.00 + 88.40 = 105.40
105.40 + 47.60 = 153.00
70% - 20% = 50%
$153.00 divided by 50% = $76.50