Arithematic

[CrackXam]

1.0003x0.9997-1.0005x0.9995 = ?

 

0.00000002

0.00000016

0.000002

0.000016

0.00000015

[MBAtoddler]

IMO - 0.00000016

product of 7 and 3 ends in a 1 and the product of 5and 5 ends in 5 in the units digit - the different should be 6 and 8 decimal places away . hence I choose my answer.

[CrackXam]

Please consider this:

1/10^4{(10^4 + 3)(10^4 - 3)-(10^4 + 5)(10^4 - 5)}

=> 1/10^4{(10^8 - 9) - (10^8 - 25)}

=> 1/10^4{-9 + 25} = 16/10^4 = 0.0016

 

Where did I go wrong?

[CrackXam]

IMO - 0.00000016

product of 7 and 3 ends in a 1 and the product of 5and 5 ends in 5 in the units digit - the different should be 6 and 8 decimal places away . hence I choose my answer.

 

i did not get this. can you please elaborate?? How did u arrive at the number of decimal places so quickly?

[MBAtoddler]

i did not get this. can you please elaborate?? How did u arrive at the number of decimal places so quickly?

 

 

u multiplying 2 numbers - the number of decimal places is the sum of the decimal places on both the numbers. 4+4 = 8

[MBAtoddler]

Please consider this:

1/10^4{(10^4 + 3)(10^4 - 3)-(10^4 + 5)(10^4 - 5)}

=> 1/10^4{(10^8 - 9) - (10^8 - 25)}

=> 1/10^4{-9 + 25} = 16/10^4 = 0.0016

 

Where did I go wrong?

1/10^4{(10^4 + 3)(10^4 - 3)-(10^4 + 5)(10^4 - 5)}

 

its 1 / 10^8 [ 10^ 4 for each equation in the first term ]

[CrackXam]

i get it. thanks :)

[go4mba]

1.0003x0.9997-1.0005x0.9995

 

can be written as

[(1+0.0003)(1-0.0003)] - [(1+0.0005)(1-0.0005)]

 

= (1-0.00000009) - (1-0.00000025)

 

= 0.00000016

[nikiforos]

Another vote for B

[aru4912]

I too did the mistake that CrackXam did (did'nt calculate the number of 0's correctly after multiplication).Now I realize that it is B.

[surya167]

B it is... We can directly calculate such questions without much trouble

[1bbinfo]

Another vote for B.