Answer: the original temperature is
123 °Fahrenheit
Step-by-step explanation:
The temperature dropped 11 Fahrenheit per hour from the original temperature. This means that the rate at which it is dropping is in arithmetic progression.
The formula for determining the nth term of an arithmetic sequence is expressed as
Tn = a + d(n - 1)
Where
a represents the first term(original temperature) of the sequence.
d represents the common difference.
n represents the number of terms(hours) in the sequence.
From the information given,
d = - 11 degrees (it is decreasing)
When n = 4 hours, T4 = 90
We want to determine the value of the first term, a. Therefore,
T4 = 90 = a - 11(4 - 1)
90 = a - 11 × 3
90 = a - 33
a = 90 + 33
a = 123 °Fahrenheit
