A bag contains coloured balls. A ball is taken at random from the bag, its colour is noted, and the ball is replaced.
A second ball is taken at random from the bag, its colour is noted, and the ball is
replaced.
The probability that the ball is red is 0.2.
First ball
Second ball
0.2
Red
Red
0.2
0.8
Not red
0.2
Red
0.8
Not red
0.8
Not red
Work out the probability that only one of the two balls taken is red.

sites:

the solution of the equation is 2.23 ⇒ answer b

step-by-step explanation:

* lets revise the meaning of exponential function

- the form of the exponential function is y = ab^x, where a ≠ 0, b > 0 ,  

  b ≠ 1, and x is any real number

- it has a constant base b

- it has a variable exponent x

- to solve an exponential equation, take the log or ln of both sides,  

  and solve for the variable

* lets solve the problem

∵

- the base is 7 and the exponent is x

- insert ㏑ in both sides

∴

- use the rule

∴ x ㏑(7) = ㏑(77)

- to find x divide both sides by ㏑(7)

∴

* the solution of the equation is 2.23 to the nearest 2 decimal places