Percentage

[ThanksForHelping]

Suppose the number of animals in a national park increases by 60% every month. By the end of December 2020, if the number of animals in the national park was 2560 , how many animals would have been there in the national park by the end of November 2020?

 

[Deleted member 4993]

Suppose the number of animals in a national park increases by 60% every month. By the end of December 2020, if the number of animals in the national park was 2560 , how many animals would have been there in the national park by the end of November 2020?

Have you worked with Geometric series?

Please show us what you have tried and exactly where you are stuck.

Please follow the rules of posting in this forum, as enunciated at:

READ BEFORE POSTING​

Please share your work/thoughts about this problem.

 

[ThanksForHelping]

Have you worked with Geometric series?

Please show us what you have tried and exactly where you are stuck.

Please follow the rules of posting in this forum, as enunciated at:

READ BEFORE POSTING​

Please share your work/thoughts about this problem.

Geometric series? No, not yet Sr.

Well I understood that by end of the year (Dec) the park has 2560 animals including the 60% increase.
So I tried to find the 60% of 2560 which is 1530 more animals in Dec.

So then I tried to subtract this increased value from Dec: 2560 - 1530 = 1030
I thought this final result 1030 would correspond to the number of animals in November
But apparently, I'm very very wrong

 

[Dr.Peterson]

Geometric series? No, not yet Sr.

Well I understood that by end of the year (Dec) the park has 2560 animals including the 60% increase.
So I tried to find the 60% of 2560 which is 1530 more animals in Dec.

So then I tried to subtract this increased value from Dec: 2560 - 1530 = 1030
I thought this final result 1030 would correspond to the number of animals in November
But apparently, I'm very very wrong

The trouble is, the increase is supposed to be 60% of the number in November, not of the number in December. Do you see that?

So a 60% increase from 1030 would mean adding 60% of 1030, which is 618, not 1530.

We'd commonly solve this with algebra, letting the number in November be x. But you can do it with mere arithmetic if you observe that 100% + 60% = 160%. Do you see how this can be useful?

 

[Deleted member 4993]

Have you worked with Geometric series?

Please show us what you have tried and exactly where you are stuck.

Please follow the rules of posting in this forum, as enunciated at:

READ BEFORE POSTING​

Please share your work/thoughts about this problem.

I misread the problem - I thought the December was next years December i.e. 13 month.

Since we are considering only one month - there is no series involved.

 

[ThanksForHelping]

The trouble is, the increase is supposed to be 60% of the number in November, not of the number in December. Do you see that?

So a 60% increase from 1030 would mean adding 60% of 1030, which is 618, not 1530.

We'd commonly solve this with algebra, letting the number in November be x. But you can do it with mere arithmetic if you observe that 100% + 60% = 160%. Do you see how this can be useful?

Thank you so much for your reply
I really appreciated