Question

A metal piece is heated and its temperature is noted at different intervals and recorded in a tabular form.
Time (in sec.)
2
6
10
14
Temperature (in C)
19
27
35
43
find after what time the temperature was 39^0 C????

Answer 1

Translate your data into ordered pairs in the form (time, temperature) :
(2,19), (6,27), (10,35), (14,43)

taking the slope between consecutive points shows that it is a constant 2, so
the relation is linear and can be expressed in the form y = mx + b
or
temperature = m(time) + b
we know temp = 2*time + b
sub in (2,19)
19 = 2(2) + b
b = 15

so temp = 2time + 15
when is temp = 39 ?
39 = 2*time + 15
24 = 2time
time = 12