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Thursday, November 17, 2011

Julibella's Math Question

Chapter 2.4

Question 18)
A frame measures 30 cm by 20 cm. Can you mount a square picture with an area of 500cm^2 in the frame? Explain.

So you're frame is 20cm x 30cm which gives you an area of 600cm^2. You're trying to put a picture with an area of 500cm^2 which dimensions are 22.36cm x 22.36cm. The picture will not fit because it is too big.

Question 19)
A square picture with an area of 100 cm^2 is mounted on a square piece of matting. The matting has 2.5 times the area of the picture. Is the picture is centered on the matting, what width of the matting is visible around the outside of the picture? Give your answer to the nearest tenth of a centimeter.

First find the area of the matting:
100cm^2 x 2.5 = 250cm^2

Fing the side length of the picture:
sqrt 100cm^2 = 10cm

Find the side length of the matting:
sqrt 250cm^2 = 15.81cm

Subtract side lengths to find visible matting:
15.81cm - 10cm = 5.81cm

Make equal on both sides of the picture to find width of visible matting:
5.81 ÷ 2 = 2.9cm

The width of the matting visible around the outside of the picture is 2.9cm.


  1. Great job Jb! You explained number 19 really well. However, I don't fully understand number 18, or your picture. So I suggest you maybe use a different picture which would improve your post. Also, you could have used colour to highlight important words in your post. Overall, you did an excellent job. Keep it up!

  2. Great job Julibella! :) First of all, I'd like to say fantastic job explaining #19 and showing your work. Secondly however, I sort of got confused because I didn't fully understand your picture so it made it difficult for me. Try adding some colors to contrast your post a bit better, overall you did wonderful, keep it up girl!

  3. Great job Jb!! You did a nice job on question 19. I liked how you explained things very well! Although,I somewhat got confused on question 18 because I didn't really understand the picture. Other than that, you did a wonderful job. Keep up the good work!

  4. Great post, Julibella! You explained your steps very well and your post was organized. The picture was somewhat hard for me to understand. Also, next time try adding in some colour to brighten up the key words.