Aptitude - Decimal Fraction - Discussion

These type of problems can be solved by Cross Multiplication principle.

I will try to explain with the present problem scenario

Consider (1/3) and (2/5)

STEP 1: Multiply numerator of 1st with denominator of 2nd
Multiply denominator of 1st with numerator of 2nd

STEP 2: The result is (1*5) and (3*2)
i.e.., 5 and 6
Now Check which number is greater of the two.
In this case 6>5
STEP 3: Check which fraction's numerator is part of the product
that results in greater number(6)

In this case 6 has numerator of 2nd fraction (2/5)
So we can say that (2/5) >(1/3)

SO ON WITH THE NEXT FRACTIONS ALSO

Thanks @Deepak.

If the numerator is increasing by a constant number the smaller the numerator the smaller the fraction.

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.

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.

@Shahid your cross multiplication method is great.