Data Sufficiency

TSonam, I am not getting how u get D for this Qs and Yuke, how come B for this Qs -

2)If X is a decimal number, is the tenth digit of X a zero?
(1) 16X is an integer
(2) 8X is an integer

X is a decimal number, so it can be anything from .000000...1 to .999...999 or even 12121212....32323.000000...1
We somehow don't know the exact value of X.
Now By 1, suppose 16 * .0001 = .0016 and 16 * .9999 = 15.9984
By 2, suppose 8 * .0001 = .0008 while 8 * .0434 = 3.472 and 8 * .9999 = 7.9992
In both cases, we can not come to conclusion- IMO E.

Say x = 1/8 or 1/4 or 1/2 ...

From 1 16X is an integer ..not putting above values in 1 we get that tenth digit is not zero

Hence sufficient


From 2 also we get the same thing ..

Hope this helps