Area of rectangle

Question

Dear Tutor,

my my daughter learned Area of Rectangles in math.  There are some questions we have little confused.  Please explain to us and the answers.  Thank you very much.

 

problem#1:  

an artist paints a murals that is 3 feet long and 5 feet wide.  She paints a second mural that is 5 feet long and 5 feet wide.  A third mural is 7 feet long and 5 feet wide.  Explain how the areas of the murals change.

 

problem#2:

Maya has a paint canvas that is 2 feet lOng and 4 feet wide.  Another canvas is double the length and width of the first canvas.  How does the area change?

  A.  It is doubled

  B.  It is 3 times greater

  C.  It is tripled

  D.  It is 4 times greater

 

Answer 1

problem 1.  The area of each mural is calculated as the area of rectangles.

 

The area of a rectangle is length times  width.

The first mural has an area of15 square feet.  The second mural has an area of 25 square feet. 

The third mural has an area of 35 squared feet.  The areas increased by 10 square feet.

 

problem 2.  you can do this problem by simply plugging in the numbers.  Doubling the dimensions makes the canvas 4 feet long and 8 feet wide.  Thus, the area will be 32 square feet.

 

You can also use the fact that doubling both length and width is like 4 times-ing the area.  Answer is D.