Fundamentals of mathmatics

[shirahudson]

Hi, I'm having trouble setting up this problem: About 3/20 of all households own two of a particular item. Approxeiamately 5/20 of all households own 3 or more of this tem. What fraction of households own 2 or mor of the items?

 

[JeffM]

Hi, I'm having trouble setting up this problem: About 3/20 of all households own two of a particular item. Approxeiamately 5/20 of all households own 3 or more of this tem. What fraction of households own 2 or mor of the items?

Suppose I told you that 3 households in a particular block of a particular town have exactly 2 of a particular item and 5 households in the same block have 3 or more of that item. How many households have 2 or more of that item?

Suppose I told you that there were 20 households on that block. What ratio of households have exactly 2 of that particular item? What ratio of households have three or more? What ratio have two or more?

Don't let ratios scare you.

 

[HallsofIvy]

I wonder why \(\displaystyle \frac{3}{20}+ \frac{5}{20}= \frac{8}{20}= \frac{2}{5}\) didn't immediately occur to you?