Investment made in one of the account is $1000 and investment made in other account is $3000.
Further, it is given that interest rate in both the accounts is same and the period for which the amount is invested is also same.
Interest = Principal * Rate * Time /100
So in case of 1st account,
Interest = 1000 * Rate * Time/100
and for the second account,
Interest = 3000* Rate * Time /100
So, comparing above two interest, it is evident that $3000 account will earn three times the amount of interest.
Hope it helps.
Thank you ..!!