ian invested $8000 part at 9% per anum and the remainder was at 10% per anum. after one year

To calculate the total amount after one year, we need to calculate the interest earned by each part and then add them together.

First, let's calculate the interest earned on the $8000 invested at 9% per annum:

Interest = Principal * Rate * Time

Interest = $8000 * 9% * 1

Interest = $8000 * 0.09 * 1

Interest = $720

Now, let's calculate the interest earned on the remainder, which is $8000 - $720 = $7280 invested at 10% per annum:

Interest = Principal * Rate * Time

Interest = $7280 * 10% * 1

Interest = $7280 * 0.1 * 1

Interest = $728

Now, let's add the interest earned on both parts:

Total amount = $720 + $728

Total amount = $1448

Therefore, the total amount after one year is $1448.

To calculate the total interest earned after one year, we need to find the interest earned on each portion of the investment.

Let's start by calculating the interest earned on the $8000 invested at 9% per annum.

Interest = Principal * Rate * Time

Principal = $8000
Rate = 9% = 0.09 (converted to decimal)
Time = 1 year

Interest = $8000 * 0.09 * 1
Interest = $720

So, the interest earned on the $8000 portion is $720.

Now, let's calculate the interest earned on the remainder, which is the difference between the total investment and the $8000.

Remainder = Total investment - $8000
Remainder = $8000 - $8000
Remainder = $0

Since the remainder is $0, we don't need to calculate the interest earned on it.

Therefore, the total interest earned after one year is $720.