IIT JEE , AIEEE Forum - Mathematics , Algebra

khushi

There are four weights 1, 1/2 ,1/4 , 1/8 [kg].what is the total weight of all possible weighings.

joyfrancis

is the ans 65/4

joyfrancis

1. taking 1 weight at a time -->Total weight=15/8

2. Taking 2 at a time (6 cases)---> Total weight = 45/8(by adding up all possible 2 at a time selections)

3. similarly for 3 at a time(4cases) = T.W=45/8

4. All four at a time --->TW=15/8

Total = (15+45+45+15)8 = 15 KG

khushi

sorry.The ans is 15kg

joyfrancis

ya ya...i got it as 15...did a silly mistake in adding up.
Did you get the method.?you only have to make cases and add up the total weight for all the cases.

thanks....

priyesh

Hi joyfrancis u made a mistake the answer is 15

in the third case when we take three at a time

the total weight comes out as 45/8 and not 55/8 check ur calculation

rest is correct

therefore on adding we get 120/8 = 15

Oh! while i was writing my reply u figured out ur mistake

neways well done

iitkgp_bipin

Well done joyfrancis.

Taking wt 1 at a time : 15/8 kg

Taking wt 2 at a time : 45/8 kg

Taking wt 3 at a time : 45/8 kg

Taking wt 4 at a time : 15/8 kg

Hence total weight = 15 kg

Ask & Discuss Questions with Community & Experts