Some people think using magnets can reduce back pain. Two groups of people suffering from back pain are given treatments to test this theory, one group is treated with magnets and the other group is treated with nonmagnetic pieces of metal. Reduction in pain is measured with a scale from 0 to 1, where the larger the number, the larger the pain reductions. Below is a summary of the results: Magnets Nonmagnetic Sample Size 20 20 Sample Mean 4.7 4.4 Sample Standard Deviation s 1.2 1.4 a. Find a 90% confidence interval for the differences in the mean pain reduction.
b. Is there evidence that Magnets help reduce back pain?

35-60 students are taking math.

answer: yes, since the line has a steeper rate of change than the exponential the y-values will be greater and they will only intersect one time.

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

the answer is c 150

step-by-step explanation: