Aptitude - Decimal Fraction
21.
0.23 − 0.0230.0023 ÷ 23 = ?
Answer
0.23 − 0.0230.0023 ÷ 23 = 0.2070.0001 = 2070
Answer :
Option CExplanation :
0.23 − 0.0230.0023 ÷ 23 = 0.2070.0001 = 2070
22.
If a = 4.965, b = 2.343 and c = 2.622, then (a3 − b3 − c3 − 3abc) =
Answer
a + (− b) + (− c) = 4.965 − 2.343 − 2.622 = 0
∴ a3 + (− b)3 + (− c)3 = 3 x a x (− b) x (− c)
⇒ a3 − b3 − c3 − 3abc = 0
Answer :
Option DExplanation :
a + (− b) + (− c) = 4.965 − 2.343 − 2.622 = 0
∴ a3 + (− b)3 + (− c)3 = 3 x a x (− b) x (− c)
⇒ a3 − b3 − c3 − 3abc = 0
23.
2.75 + 3.78 = ?
Answer
2.75 + 3.78 = −2 + 0.75 − 3 + 0.78 = − 5 + 1.53 = − 4 + 0.53 = 4.53
Answer :
Option CExplanation :
2.75 + 3.78 = −2 + 0.75 − 3 + 0.78 = − 5 + 1.53 = − 4 + 0.53 = 4.53
24.
The number whose square is equal to the difference of the squares of 75.15 and 60.12 is
Answer
x2 = (75.15)2 − (60.12)2 = (75.15 + 60.12)(75.15 − 60.12)
⇒ x2 = 135.27 x 15.03 = 9 x 15.03 x 15.03
⇒ x = √9 x 15.03 x 15.03 = (3 x 15.03) = 45.09.
Answer :
Option AExplanation :
x2 = (75.15)2 − (60.12)2 = (75.15 + 60.12)(75.15 − 60.12)
⇒ x2 = 135.27 x 15.03 = 9 x 15.03 x 15.03
⇒ x = √9 x 15.03 x 15.03 = (3 x 15.03) = 45.09.
25.
1 litre of water weighs 1 kg. How many cubic millimetres of water will weigh 0.1 gm ?
Answer
1000 gm is the weight of 1000 cu. cm of water.
1 gm is the weight of 1 cu. cm = 1000 cu. mm
0.1 gm is the weight of (1000 x 0.1) cu. mm = 100 cu. mm
Answer :
Option AExplanation :
1000 gm is the weight of 1000 cu. cm of water.
1 gm is the weight of 1 cu. cm = 1000 cu. mm
0.1 gm is the weight of (1000 x 0.1) cu. mm = 100 cu. mm
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