15. At what rate per cent of interest will a sum of money become 6 times itself in
15 years?​

The rate of interest will be 40%

Step-by-step explanation:

So first consider the principal to be x

Then the SI (Simple interest) will become six times of itself that is 6x

The time is 15 years

Rate = SI × 100 / P × T

Now put the values

Rate = 6 × x × 100 / x × 15

Then after simplifying the rate will come 40 %

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)

d. vertex

step-by-step explanation: