If 5a.b is a decimal with 5, a, and b as the tens, ones, and tenths

Question

If 5a.b is a decimal with 5, a, and b as the tens, ones, and tenths digits, respectively, what is the value of b?

(1) If 5a.b were rounded to the nearest whole number, the new number would be 52.
(2) 5a.b/9 converts to a terminating decimal.

Abhini26 · Answer

Ans is d.. 
Statment 1 is insufficient by itself as no unique sol is generated. a can be 1,2 and b can be 0-9 depending on value of a.
Statment 2 is insufficient by itself. However we can deduce that a+b = 4, 13.
On combining both statments a unique sol is obtained

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debtanuB · Answer

from (1), it could be any no. for eg-51.6, 51.7, 51.8, 51.9 =>not sufficient.
from (2), it could be any no. for eg-58.5, 50.4, 54.9, etc (the sum of digits should be divisible by 9 as the decimal is terminating) =>not sufficient
from (1) & (2), it could 52.2 only (the no. 51.3 if you are thinking can be rounded to 51 & not 52).
So, b=2 =>(1) & (2) together sufficient.

adkikani · Answer

VeritasKarishma   amanvermagmat   Bunuel   chetan2u   gmatbusters   Abhishek009   Gladiator59

Can you advise if below line of thoughts is correct:
for a fraction to reduce to terminating decimal, I need either 2 or 5 OR BOTH
in the denominator, since st 2 has 9 in the denominator and WE ARE GIVEN that the
fraction reduces to terminating decimal, we need to cancel out 9 i.e. we must have
multiple of 9 in the numerator.

Let me know our thoughts choosing on B vs C

navzie · Answer

Statement one & two both are not sufficient alone.

But when taken together, the only possible value where we get terminating decimal is 52.2. Both can be rounded to 52.

Answer: C

coolavis · Answer

Statement 1 alone can be any of these 51.5, 51.6, 51.7.....52.1, 52.2,52.3,52.4 So it's not sufficient.

Statement 2 alone can be 50.5, 54.0, 54.9 etc so not sufficient.

St 1+2: 52.2 is the only option that is divisible by 9 (sum of digits should be divisible by 3 and 9). Hence sufficient.

Ans C

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bumpbot · Answer

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If 5a.b is a decimal with 5, a, and b as the tens, ones, and tenths

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GMAT Data Sufficiency (DS) Questions

If 5a.b is a decimal with 5, a, and b as the tens, ones, and tenths

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