Answer:
30 minutes will it take to reach its specified operating temperature from 25°C.
Step-by-step explanation:
Initial Temperature of oven = 25°C
Time taken by oven to reach 85°C temperature = 15 minutes
We have to find time taken by oven to reach at temperature of 145°C
Increase in temperature in 15 minute = 85 - 25 = 60°C
So, Time take by oven to increase 60°C temperature = 15 min
Time take by oven to increase 1°C temperature = 
Temperature we have to increase = 145 - 25 = 120°C
Time take by oven to increase 120°C temperature = 
Therefore, 30 minutes will it take to reach its specified operating temperature from 25°C.
To find the percentage of 28 from 70:
28/70=0.4
0.4=40%
Answer:
-197.2
Step-by-step explanation:
Since it is arithmetic series, first find the difference d between the two know series.
3.8 - 6 = - 2.2
d = -2.2
a = 6
Tn = -29.2
Looking for the n term, use the linear method.
Tn = a+( n - 1)d
Substitute all the parameters
-29.2 = 6+( n - 1 ) -2.2
-29.2 = 6 - 2.2n + 2.2
- 29.2 = 8.2 - 2.2n
-29.2 - 8.2 = - 2.2n
-37.4 = -2.2n
n = 37.4/ 2.2
n = 17 terms.
To Find the exact sum of the arithmetic series, use the sum formula below
Sm = n/2( 2a + (n - 1)d)
Sm = 17/2( 2 × 6 + ( 17 - 1 ) -2.2
Sm = 17/2(12 - 35.2)
Sm = 8.5( - 23.2)
Sm = - 197.2
Therefore, the exact sum of the arithmetic series is -197.2