Johnny ran 20 laps around a circular field. If he covered a distance of 3265.6 metres, what is the radius of the circular field?

60?

Step-by-step explanation:

2πr = 163.28

20(2πr) = 3265.6

r ≈ 60.927382

25.99 metres

Step-by-step explanation:

2πr is the circumference equation for the distance of one lap. Multiply that by 20 to get the distance of the laps in total. Then, simplify with r (radius) as the variable to solve for.

20(2πr) = 3265.6

2πr = 163.28

r ≈ 25.986819108

26

step-by-step explanation:

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