Ucat decision making help

Hi there, I could not solve this. Are there any solutions available?

How would you draw the venn diagram for this question as i don’t really get why it’s C

This is how I thought about it:


Why it can be C:

To own only a TV and ipad it has to be within the yellow section of the diagram. The reason why this is, is because an owner of an ipad has to either:

-also own a tv

-also own a tv and a stero (we known there are 12 households like this).

So we have to remove the latter option to get 'own a tv and ipad'.

The yellow section is equal to 35 (total of ipad users) minus 12 (ipad users which also own a stereo and tv), thus 35-12=23.



Why it isn't B imo:

There are 85 families which have a tv. We also know that if you have an ipad or stereo (or both) you also have a tv. We also know that every household that has one of the smaller devices also has a tv. So in summary, the households can have either:

- only a tv

- tv and ipad (35-12)

- tv and stereo (40-12)

- all three ( we know its 12)

- nothing



So, to calculate the amount of families with only tv we have to remove all the other household device options;

(All tv users) - [ (tv and ipad) + (tv and stereo) + (all three)] = (Only tv)

85 - [ (35-12) + (40-12) + 12] = Only tv

85 - [ 23 +28 +12] = Only tv

85- 63 = Only tv

22 = Only tv, which is different from 10