Aptitude Decimal Fraction Test Paper 4

16) Which of the following fraction sets of fractions is in descending order?

3/5, 7/9, 6/7
7/9, 3/5, 6/7
7/9, 6/5, 3/5
6/7, 7/9, 3/5

Answer: D

Explanation:

Convert each fraction in decimal form, we get
3/5 = 0.6
7/9 = 0.777
6/7 = 0.857
Clearly, 0.857>0.777>0.6
Or, 6/7>7/9>3/5.

17) What is the HCF and LCM of 3, 2.7, and 0.09?

0.03, 2.7
0.03, 0.27
0.3, 0.027
3, 27

Answer: B

Explanation:

Make the same number of decimal places. The given numbers are 3.00, 2.70, and 0.09.
Without decimal places, these numbers are 3, 27, and 9.
Now, the HCF of 3, 27, and 9 is 3.
So, the HCF of 3, 2.7, and 0.09 is 0.03
Now, the LCM of 3, 27, and 9 is 27.
So, the LCM of 3, 2.7, and 0.09 is 0.27

18) If 1.125 * 10^k = 0.001125, the value of k is

-4
-5
-3
-1

Answer: C

Explanation:

The given expression is 1.125 * 10^k = 0.001125
Or, we can say 0.001125 = 1.125/10³ = 1.125 * 10^-3
Now, 1.125 * 10^k = 1.125* 10^-3
On comparing both sides, we get 10^k = 10^-3
Hence, k = -3

19) A meter is taken to be equal to 39.3701 inches. If the value is approximated to 39+[7/20] inches, the relative percentage error is

5%
0.05%
0.005%
0.5%

Answer: B

Explanation:

A meter is exactly equal to 39.3701 inches
The approximate value = 39+ [7/20] = 39.35 inches

The relative percentage error = [[actual value - approximate value]/ [actual value]] *100
Or, error % = [[39.3701 - 39.35]/ [39.3701]]* 100
Or, error % = [0.0201/ 39.3701] * 100
Or, error % = [20100/393701] = 0.05%

20) If 1.5a = 0.04b, the value of [(b-a)/ (b+a)] is

730/77
73/77
7.3/77
None of these

Answer: B

Explanation:

We can write the expression 1.5a = 0.04b as a/b = 0.04/1.5
That means a = 0.04, and b = 1.5
Now put the value of a and b in [(b-a)/ (b+a)]
We get, (1.5 - 0.04) / (1.5+0.04) = 1.46/ 1.54
Or, we can say 146/154 = 73/77