If sally got 28 questions correct and received 70% on the exam, how many questions were on the exam

40

Step-by-step explanation:

Number of correct questions Sally got = 28 questions

Percentage of correct questions answered= 70% on the exam,

Total number of questions in the exam = Unknown

Let the total questions in the exam be represented as y.

Since Sally got 70% correctly, this will be:

70% of y = 28

70/100 × y = 28

0.7 × y = 28

0.7y = 28

Divide both side by 0.7

0.7y/0.7 = 28/0.7

y = 40

There are 40 questions in the exam.

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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