# What is the answer to this scientifical math problem?

I’m having problem figuring this question out: Assume the brain is 70% water. If the average adult human brain weighs 1.4 kg, how many kilograms of water does it contain? Thank you for any help.

density of water is 1g/m^3

so, 75/1001.4kg x 1m^3/gram 1000gram /kg = 980 grams. (use conversion factors, they are really the easiest)

.98 but I’m sure you figured that out already :P

1.4 x 0.7 = 0.98 kg

to figure this out

100% of the brain = 1.4 70% of the brain = x

cross multiply

100% of the brain multiplied by x = 1.4 x 70% of the brain

100% = 100/100 = 1 70% = 70/100 = 0.7

1x = 1.4 x 0.7 x = 0.98

To figure it out simply multiply 1.4 by .7 and you will get the percentage made up by water.

Thanks for the correction, wasn’t thinking to well since I did something entirely different to find the answer lol.

yep but shouldnt the 70 be multiplied?

Your answer is 980 grams of water or .98 kilograms of water.

How did I find the answer? I took the weight of the brain and converted it into grams which is 1400 grams. Then I multiplied that by .7 and I got 980. Then I converted that value into kilograms which ended up being .98

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