Madeleine invests £8000 in an account for one year. At the end of the year, interest is added to her account.
Madeleine pays tax on this interest at a rate of 20%
She pays £35.20 tax.
Work out the percentage interest rate for the account.

y

Step-by-step explanation:

El Pepe

Step-by-step explanation:

1 number

if we use a graphing calculator, there is only one such number that satisfies the conclusion of the mean value theorem, that is, a number such that

where the right-hand side is the average rate of change of f on the interval [0.5,0.75], which is the slope of the secant line.

in the attached graph, the black line is the secant line which has its slope as the average rate of change of f on [0.5,0.75], while the orange line is the only tangent line to the graph of f in the interval that satisfies the mvt conclusion.