When Raul began seventh grade he put his savings of $3000 in an account that compounds interest annually. He hopes to have $6000 by the time he graduates high school in six years. What interest rate is required for him to reach his goal?

  12.25%

Step-by-step explanation:

Raul needs to find the value of r such that ...

  A = P(1 +r)^t . . . . . formula for future value of P at interest rate r

  6000 = 3000(1 +r)^6 . . . . with given numbers

  2 = (1 +r)^6 . . . . . . . . . . . . . divide by 3000

  2^(1/6) = 1 +r . . . . . . . . . . . . take the 6th root

  2^(1/6) -1 = r ≈ 0.1225 = 12.25%

Raul needs an interest rate of 12.25% to reach his goal.

Check

Raul wants to double his money in 6 years. The "rule of 72" says the product of doubling time and percent interest rate is about 72. For a 6-year doubling time, that suggests Raul needs an interest rate of about 72/6 = 12 percent. This is close to what we calculated.

since your problem is x^4 = 81, what you have to undeo is the "to the fourth power" part.

the inverse (opposite operation) of "to the fourth power" is "to the fourth root".

  (x^4) ^ ¼   = 81 ^ ¼  

  81 = 3^4     so (3 ^ 4) ^ ¼   =   3 ^ 1   = 3

by hand: (3 ^ 4) ^ ¼   =   3 ^ (4 x ¼) = 3 ^ 1   = 3   (when you take a power to a power, multiply the exponents.)

or, do it by calculator. one way of finding the fourth root is to use ^ (1/4)

step-by-step explanation:

25 questions , because they start with 100.  

350-100=250 .  

. 250/10=25

step-by-step explanation:

first take off 100, then what x 10 = 250? that is your answer. (25)