Aptitude - Time and Work - Discussion

Tanya does 25% efficient work. What does this mean? This means that the work that Sakshi completes is 100% and Tanya does the same work but 125%. So see efficiency as the greater percentage of work being done by Tanya 125% is greater than 100%.

For example if a does 20 units of work in 5 hrs and b does 40 units of work in 5 hrs. Then 1 hr work of A and B is 4 and 8 respectively. What does this mean? It means that B is doing more work in same no of hrs.

Now consider it as B was doing 40 units of work in 5 hrs. So what is his time for 1 unit of work? its 5/40. i.e 1/8! and similarly for A it is 1/4. So in respect of timing who is fast or efficient? Its certainly B because 1/8 is smaller than 1/4!

@Sujith and @Sandeep

You are wrong.

The given ratio is about "TIME TAKEN" not the ratio of work done.

If Tanya is more efficient (25%) than Sakshi - means Tanya will take less time than Sakshi to complete the work.

We can say the same thing in another way, i.e., Sakshi is 25% INEFFICIENT than Tanya. So, if Tanya takes 100 hours to complete a task then Sakshi will take 125 hours (25% extra than Tanya) to complete the same task.

So, time taken by
Tanya = 100 hours ,
Sakshi = 125 hours.

Therefore, Ratio of times taken by Sakshi and Tanya = 125 : 100 = 5 : 4.

This is what the first line in the given explanation.

Hope this will help you. Have a nice day!

@All.

Here Tanya is 25% more efficient than Sakshi. So why can't we take Tanya as 100 and Sakshi as 75. It can be understood from the basic concept of percentages that if A is 25% more than B, B is how much percent less than A and that will never be 25.

Let B=100 => A=125. Difference= 25. How much is B less than A = (25/125)*100 = 20%. The change is to be taken from A i.e 125 and not 100.

Similarly, if Tanya is 25% more efficient than Sakshi, then Sakshi is 20% less efficient than Tanya and not 25%.

So going by this, if you take 80 instead of 75, you will get the same answer which is also the only correct answer.

@All.

The sentence 'Tanya is 25% more efficient than Sakshi' means Tanya will take 25% less days than Sakshi and not that Sakshi will take 25% more days than Tanya. The answer given assumes the later part which is not correct. Percents work differently for the increase and decrease.

For example, 25% more than 100 is 125. But 25% less than 125 is not a hundred.

The answer would be 16 if the question had been stated as Sakshi is 25% less efficient than Tanya.

See This for those Who do Time and work with LCM..

It is said that Sakshi can do a piece of work in 20 days with her efficiency so we cannot take 25%of 20.

Here it is given 25% more efficient.
So efficiency of Sakhsi : Tanya.

Assume: S:T = 100unit : 125 unit (25%more).

Therefore ,
Total work = 100unit x 20days.
:. Tanya would do the same work in:
Total work/ Tanya efficiency,
:. 100unit x 20/125= 16 days.

@Oakley.

Efficiency: When we say Tanya is 25% more efficient than Sakshi, it means Tanya can do 25% more work in the same amount of time compared to Sakshi. This directly affects the number of days she will take to complete the work.

Efficiency does not directly translate to days: If Tanya is 25% more efficient, it doesn't mean she will take 25% fewer days. Instead, her work rate is 25% higher.

Sakshi can do a piece of work in 20 days and Tanya is 25% more efficient than Sakshi that means

125% of Work by Sakshi in ------------> 20 days.
100% of Work by Tanya ---------------> x.


By Cross Multiplication we get;

125% * x = 100% * 20,
=> (125/100) * x = (100/100) * 20,
=> x = (100/125) * (100/100) * 20,

After Cancellation You'll get Result as 16 days.

@All.

Tania is 25% more efficient then Sakshi so we can do it like,
Tania=125 units/day, Sakhi = 100 units/day.
As Sakhi done it in 20 days so we can find complete work done,
Total work= 20 * 100 = 2000.

We also have Tania unit work so we will divide total work with Tania unit work,
Tania work= 2000/125 = 16 answer.

The answer is 15 let me tell you.

Tanya is 25% efficient than Sakshi.

If Sakshi do a work in 24 hours then Tanya will do in 18 hours because 12 is 50% of 24. 6 is 25% of 24.

So Tanya take 6 hours less time than Sakshi, so reduce 6 hours in every day upto 20 days 6 x 20 = 120 i.e 5 days.

20 days - 5 days = 15 days.

@Vamshidar reddy, Preethy& Samar;.

The answer 16 is justified.

Given that Tanya is more efficient than Sakshi. So, Tanya will take less time to complete the work.

If Tanya is 25% more efficient than Sakshi, it is not nessesary.

That Tanya will complete the work in 25% of the days less than Sakshi.