A math question......

[RStar]

Math is not my best subject (only second worst to spelling!).

I'm going nuts trying to figure out how to do this.

How do I figure what % of 7 is 4.8?

It seems so simple, yet.......

[blueerica]

I think it's 68.57%. You should be able to just divide 4.8 by 7.

[blueerica]

I also am a heavy user of the cross-multiply and divide technique, which is a way I tend to represent "this is to this as that is to that" mathematically. So, you could cross-multiply 4.8 and 100 to get 480. Then divide that by 7 which equals the same thing I told you earlier. Sort of a 4.8 is to 7 as X is to 100 set up.

I think I made that more complicated than it needed to be.

[BarTopDancer]

Originally Posted by blueerica

I also am a heavy user of the cross-multiply and divide technique, which is a way I tend to represent "this is to this as that is to that" mathematically. So, you could cross-multiply 4.8 and 100 to get 480. Then divide that by 7 which equals the same thing I told you earlier. Sort of a 4.8 is to 7 as X is to 100 set up.

I think I made that more complicated than it needed to be.

Brain melting.

[Kevy Baby]

Originally Posted by blueerica

I think I made that more complicated than it needed to be.

Yep!

[Drince88]

Originally Posted by blueerica

I think I made that more complicated than it needed to be.

Yes - but you did make me smile. My Mom's theory of practical math is that everything that isn't simple arithmetic can be expressed in a ratio problem. And I've found very few examples where that wasn't true. Most of what I do know is making units cancel, which is another way of looking at ratios!

[Alex]

Originally Posted by Drince88

Yes - but you did make me smile. My Mom's theory of practical math is that everything that isn't simple arithmetic can be expressed in a ratio problem. And I've found very few examples where that wasn't true. Most of what I do know is making units cancel, which is another way of looking at ratios!

Assuming a constant rate of water being added, if you overfill your old-fashioned clawfoot bathtub what will the upward velocity of your rubber ducky be at the moment the tub reaches capacity and begins to overflow?

What? That was what constituted practical math in my calculus classes.

But yeah, for figuring out percentages I use the cross multipication method. Or if an estimate is sufficient I would have said that since 7 is approximately 1/14th of 100 then just multiply 5 by 14 to get 70 and then subtract -- to get back to 4.8 from 5 -- .2 x 14 (2.8) to get an approximate answer (67.2%) which isn't all that far from the correct number (68.6%) and is all math that is easily done mentally.

[Cadaverous Pallor]

Originally Posted by blueerica

Sort of a 4.8 is to 7 as X is to 100 set up.

I totally use this method. It's the only way I can remember the relationships. It takes a few steps but it's always right

[Kevy Baby]

Originally Posted by Cadaverous Pallor

I totally use this method. It's the only way I can remember the relationships. It takes a few steps but it's always right

Maybe I am missing something, but I always believe it is better to KISS (Keep It Simple Stupid*). By adding steps, you introduce additional opportunities to make a mistake.

In the grand scheme of things, it doesn't matter all that much though.




* No, I am not calling anyone stupid: it is just the acronym

[Drince88]

Originally Posted by Kevy Baby

Maybe I am missing something, but I always believe it is better to KISS (Keep It Simple Stupid*). By adding steps, you introduce additional opportunities to make a mistake.

Yes, you do introduce opportunities - but if you're starting from a known correct place vs a potentially wrong place, it's better to go the long way around and double check for mistakes, then not know if you're in the right starting place.