MathRevolution wrote:
[
Math Revolution GMAT math practice question]
\([x]\) is the greatest integer less than or equal \(x\), what is the value of \([√30]+[√40]+[√50]?\)
\(A. 12\)
\(B. 15\)
\(C. 16\)
\(D. 18\)
\(E. 20\)
GIVEN: [x] is the greatest integer less than or equal x For example, [3.2] = 3, since 3 is the greatest integer that is less than (or equal) to 3.2
Likewise, [8.7] = 8, since 8 is the greatest integer that is less than (or equal to) 8.7
Now onto the question....
√25 = 5
√36 = 6
√49= 7
√64 = 8
Since √30 is BETWEEN √25 (aka 5) and √36 (aka 6), we know that √30 = 5.something
So, [√30] = 5
Since √40 is BETWEEN √36 (aka 6) and √49 (aka 6), we know that √40 = 6.something
So, [√40] = 6
Since √50 is BETWEEN √49 (aka 7) and √64 (aka 8), we know that √50 = 7.something
So, [√50] = 7
So, [√30]+[√40]+[√50] = 5 + 6 + 7 = 18
Answer: D
Cheers,
Brent
_________________
Brent Hanneson – Creator of gmatprepnow.com
I’ve spent the last 20 years helping students overcome their difficulties with GMAT math, and the biggest thing I’ve learned is…
Students often get questions wrong NOT because they lack the skills to solve the question, but because they don’t understand what the GMAT is testing Learn more