Using Goal Seek in Excel to solve algebra equation: A dangerous virus is spreading...

[oregon789]

A dangerous virus is spreading through a population and 300 have fallen ill so far. If d stands for the number of days since Aug. 1 and N is the number of victims (in hundreds), and if N(d)=3(1.32)^d, when will the number of victims reach 4,000?

We're supposed to use Goal Seek in Excel to solve this. My calculations are giving me 4000/3.00006 which is 1333.05, so about 4 1/2 months?

 

[mmm4444bot]

A dangerous virus is spreading through a population and 300 have fallen ill so far. If d stands for the number of days since Aug. 1 and N is the number of victims (in hundreds), and if N(d)=3(1.32)^d, when will the number of victims reach 4,000?

We're supposed to use Goal Seek in Excel to solve this. My calculations are giving me 4000/3.00006 which is 1333.05, so about 4 1/2 months?

Hey oregon, washington here.

1,333 days is just over 3 years 7⅔ months.

Make sure you're using the right units for N; it represents hundreds of victims.

For example, on July 31st the value of d is zero, so we have:

N(0) = 3(1.32)^0

N(0) = 3.00

This tells us that there are 300 victims, as of the close of July 31st.

1 day later, it's August 1st, and d is 1.

N(1) = 3(1.32)^1

N(1) = 3.96

As of the close of August 1st, there are 396 victims.

At the end of the month, the value of d is 31.

N(31) = 3(1.32)^31

N(31) = 16402.62

There are 1,640,262 victims, at the close of August.

What value of N represents 4,000 victims? :cool:

 

[oregon789]

Hey oregon, washington here.

1,333 days is just over 3 years 7⅔ months.

Make sure you're using the right units for N; it represents hundreds of victims.

For example, on July 31st the value of d is zero, so we have:

N(0) = 3(1.32)^0

N(0) = 3.00

This tells us that there are 300 victims, as of the close of July 31st.

1 day later, it's August 1st, and d is 1.

N(1) = 3(1.32)^1

N(1) = 3.96

As of the close of August 1st, there are 396 victims.

At the end of the month, the value of d is 31.

N(31) = 3(1.32)^31

N(31) = 16402.62

There are 1,640,262 victims, at the close of August.

What value of N represents 4,000 victims? :cool:

OK but how would I type that in Goal Seek? It keeps running and giving me a decimal as an answer.

 

[Otis]

how would I type that in Goal Seek? It keeps ... giving me a decimal ...

I'm not familiar with Excel. Maybe there's a support forum for Excel, on the Internet.

Concerning decimal results, perhaps that's okay.

For example, the number of days for the victim count to reach 5,164 is 10.25. That's a decimal, but I'm not sure exactly what Goal Seek does or returns.

Googling keywords goal seek excel produces a lot of results. If you believe that you're using it correctly, but not getting what you expect, then your next goal could be to seek gurus at an Excel site.

Or, you can wait for somebody in the know to come across this thread. Either way, good luck!