Aptitude - Surds and Indices - Discussion

Discussion :: Surds and Indices - General Questions (Q.No.3)

3. 

Given that 100.48 = x, 100.70 = y and xz = y2, then the value of z is close to:

[A]. 1.45
[B]. 1.88
[C]. 2.9
[D]. 3.7

Answer: Option C

Explanation:

xz = y2       10(0.48z) = 10(2 x 0.70) = 101.40

0.48z = 1.40

z = 140 = 35 = 2.9 (approx.)
48 12


Fazila said: (Nov 10, 2010)  
I think its something different method.

Vignesh said: (Sep 26, 2011)  
This not the different one, as like a to the power m whole to the power of n=a to the power of m*n.

Rajesh said: (Jan 20, 2012)  
Its very Simple. If Base Values are equal of both side than power's are equal.

Adeyemi Raphael said: (Mar 5, 2012)  
Why do both side have to divided, not addtion, subtraction or mutplication to get final answer?

Sagar said: (Jun 10, 2012)  
It is very easy to solve if you know Logarithm.
Step1: Zlog(10^0.48)=2log(10^0.70)
Step2: ZX0.48=2X0.70 (Log10=1)
Step3: Z= 2.9

Roseline Aderonke said: (Nov 7, 2013)  
The workings are well understood once it is strictly followed step by step.

Sanjay said: (Aug 18, 2014)  
What is the appropriate meaning of 2^0.5?

Nego said: (Aug 2, 2015)  
I'm a bit confused about this. Why is the y2 not (0.70*0.70), rather its (2*0.70)?

Tulasi said: (Sep 10, 2015)  
10^0.48 = x //given.

10^0.7 = y //given.

x^z = (10^0.7)^2.

Since (a^m)^n = a^(m*n) we get,

(10^0.48)^z = 10^(z*0.48) and (10^0.7)^2 = 10^(0.7*2).

Now, 10^(0.48*z) = 10^(0.7*2).

Since bases are equal, equating powers we get:

z*0.48 = 0.7*2.

z = 140/48.

z = 2.9166 which is approximately 2.9.

Kumar Arpit said: (Oct 11, 2015)  
That seems correct to me. I think this is the correct way.

Thiyaguaxrev4Fvtr said: (May 26, 2016)  
How to get the answer? Please explain me.

Jaichu said: (Mar 7, 2017)  
Please explain me.

0.48z = 1.40.
z =140/48.

How could they multiply it?

Aniket Gaikwad said: (Apr 22, 2017)  
Thanks @Tulasi.

Akhila said: (Jun 14, 2018)  
@Jaichu.

For both nums decimal at the same place. So, a decimal can be removed.

Jesophat said: (Feb 1, 2019)  
48/100 = 0.48z =1.4z.

Naman said: (Feb 17, 2020)  
I cannot understand it.

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