Aptitude - Decimal Fraction - Discussion

Another simple method:

Lets option A that is:
1/3 , 2/5 , 3/7 , 4/5 , 5/6 ,6/7

Take the LCM of all the denominators which is
3,5,7,5,6,7

LCM is 210
make the denominator 210. The fraction which is
70/210 , 84/210 , 90/210 ,168/210 , 175/210 ,180/210

now we can easily compare the values because all the denominator is same.
So the decending order is:

180/210 , 175/210 ,168/210 ,90/210 ,84/210 , 70/210.

i.e.

6/7 , 5/6 , 4/5 , 3/7 , 2/5 , 1/3.

This is the answer, it is very short to solve, hope now you will got it.

By carefully watching this particular problem, we can observe that the option A,B & C numerators are in ascending order whereas the option D numerator are given in descending order.

Take LCM for the Decimals: 3, 5, 7, 5, 6, 7.
The LCM is 3*5*6*7.

Now multiply each number with (2*3*5*7)/(3*5*6*7).

We will get the numerator values as 70, 84, 90, 168, 175, 180.

No the decreasing order is : 6/7, 5/6, 4/5,3/7,2/5, 1/3.

The fraction whose numerator after cross multiplication gives the greater value is greater.

Here take the 1st two 6/7 and 5/6
6*6>5*7.

From given options option D only satisfy this...So ans is D.

@Shahid your cross multiplication method is great.

For the first three option take the 1st and last digit, then compare the two digit.

For option a), b)and c)
1/3=0.3333 and 6/7=0.8571, now we can see that 1st one is smaller then last one.

So they are not in descending order.

Hence answer is the rest means option D).

Let us check option D.

Write 6/7 = 60/7, 5/6 = 50/6, 4/5 = 40/5, and so on it makes easy to calculate. Since we converted them into improper functions.

8.5, 8.2, 8, 4.2, 4, 3.3

I did it by seeing just observe any numbers with same denominators like I supposed 7 denominator for option A I saw that 3/7 is coming before then 6/7 so option A is not in descending order, like as I tried B & C, lastly I got D which is correct for my consideration.

Observe the all options in numerators and denominators.

If numerators increases value increases. But they are asking for decreasing order.

So denominator decreases the value decreases.

So there is only one option 6, 5, 4, 3, 2, 1.

So option: D.

Check this technique:

In starting it may be consume some time but after practice we will solve in second.

6/7, 5/6, 4/5, 3/7, , 2/5, 1/7.

Check difference between numerator and denominator and then divide numerator with difference.

6-7 = 1.
6/1 = 6.

5-6 = 1.
5/1 = 5.

Don't confuse with numerator greater or smaller.

4-5 = 1.
4/1 = 4.

3-7 = 4.
3/4 = 0.7.

2-5 = 3.
2/3 = 0.6.

1-7 = 6.
1/6 = 0.1.