Question

On a cold February morning, the radiator fluid in Stanley’s car is -18 degrees When the engine is running, the temperature goes up 4.5 degrees per minute. Approximately how long will it take before the radiator fluid temperature reaches 60 degrees ?

Answer 1

Remark

This is an arithmetic progression. You have the first and last terms and the difference.

Givens

a = - 18

L = 60

d = 4.5        

Equation

L = a + (n - 1)d

Solve

60 = -18 + (n - 1) * 4.5   Add 18 to both side

60 + 18 = (n - 1) * 4.5      

78 = (n - 1) * 4.5           Divide both sides by 4.5

78/4.5 = n - 1

17.3333 = n - 1             Add 1 to both  sides.

18.3333 = n

Conclusion

It will that 18 1/3 or 18.33333 minutes to get the from -18 to 60 degrees.