A histogram is drawn with three columns whose widths are in the ratio 1: 2:4. The frequency densities of these classes are in the ratio 16:12:3, respectively,
A. Given that the total frequency of the data is 390, find the frequency of each class.

B. The classes with the two highest frequencies are to be merged and a new histogram drawn. Given that
the height of the column representing the merged classes is to be 30 cm, find the correct height for the
remaining column.

C. Explain what problems you would encounter if asked to construct a histogram in which the classes with
the two lowest frequencies are to be merged.

the answer is b

answer: the resulting cross section is a rectangle. solution: a plane parallel to the base of a triangular prism will intersect a cross section that is the same shape as its bases. so the cross section is a triangle.

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