if jeremiah has a course average score between 80 and 89, he will earn a grade of B in his history class. He has four previous exam scores of 69, 78, 81, and 92. The final exam score has twice the weight of each of the other exams. What range of scores on the final exam will earn Jeremiah a B in the course?

The range of scores that can earn Jeremiah a B in the course is 80 - 100

Step-by-step explanation:

Average = total scores/number of exams

For an average of 80, considering the final score has twice the weight of the previous exams;

Note: since the final score has twice the weight of previous exams, it is considered a double score and counted twice

Let the lowest final score for a B grade be y

80 = (69 + 78 + 81 + 92 + 2 * y)/6

80 * 6 = (320 + 2y)

2y = 480 - 320

y = 160/2

y = 80

Let the highest final score for a B grade be z

89 = (69 + 78 + 81 + 92 + 2 * z)/6

89 * 6 = (320 + 2z)

2z = 534 - 320

z = 214/2

z = 107

Since, the highest score in the exam cannot exceed 100,

Therefore, the range of scores that can earn Jeremiah a B in the course is 80 - 100

step-by-step explanation:

options

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