Answer:
<em>C(19)=12 responses</em>
Step-by-step explanation:
<u>Exponential Decay Function</u>
The exponential function is frequently used to model natural growing or decaying processes, where the change is proportional to the actual quantity.
An exponential decaying function can be expressed as follows:

Where:
C(t) is the actual value of the function at time t
Co is the initial value of C at t=0
r is the decaying rate, expressed in decimal
The company puts out an advertisement for a job opening. Initially, the company got 90 responses to the advertisement. Each day, the responses declined by 10%.
This is an example where the decay model can be used to calculate the responses to the advertisement at the day t.
The initial value is Co=90, the decaying rate is r=10% = 0.10. The model is written as:

Calculating:

We are required to calculate the number of responses at day t=19, thus:

C(19)=12 responses
Let’s say it takes time t hours for the interception.
In that time the carrier travels 28t nm west and the helicopter 130t nm.
Now we use the sine rule to find the angle x which lies between the distance 175 and 130t.
sin(x)/28t=sin35/130t. So sin(x)=28sin35/130=14sin35/65=0.1235 and x=7.0964 degrees.
Therefore the helicopter should use a bearing of 35+7.0964=42.0964 degrees north of east or 47.9 degrees east of north approx.