Aptitude - Number
21.
A number is as much greater than 22 as is less than 72. Then the number is :
Answer
Let the required number be p. Then,
p − 22 = 72 − p ⇒ 2p = 94 ⇒ p = 47
Answer :
Option AExplanation :
Let the required number be p. Then,
p − 22 = 72 − p ⇒ 2p = 94 ⇒ p = 47
22.
A two digit number is 7 times the sum of its digits. The number formed by reversing its digits is 18 less than the original number. What is the number ?
Answer
Let ten's digit be m & unit's digit be n. Then,
10m + n = 7(m + n) ⇒ 7m − 6n = 0 ⇒ m − 2n = 0 .... (i)
(10m + n) − (10n + m) = 18 ⇒9m − 9n = 18 ⇒ m − n = 2 .... (ii)
On solving (i) & (ii), we get m = 4 and n = 2 ⇒ Number = 42
Answer :
Option AExplanation :
Let ten's digit be m & unit's digit be n. Then,
10m + n = 7(m + n) ⇒ 7m − 6n = 0 ⇒ m − 2n = 0 .... (i)
(10m + n) − (10n + m) = 18 ⇒9m − 9n = 18 ⇒ m − n = 2 .... (ii)
On solving (i) & (ii), we get m = 4 and n = 2 ⇒ Number = 42
23.
The ratio between two numbers is 2 : 3. If the consequent is 24, the antecedent is :
Answer
Let the antecedent be y. Then,
y24 = 23 ⇒ y =23 x 24 = 16
Answer :
Option BExplanation :
Let the antecedent be y. Then,
y24 = 23 ⇒ y =23 x 24 = 16
24.
Find the number such that its third is greater than its fifth by 16.
Answer
Let the number be y. Then,
y3 − y5 = 16 ⇒ 5y − 3y = 240 ⇒ 2y = 240 ⇒ y = 120
Answer :
Option AExplanation :
Let the number be y. Then,
y3 − y5 = 16 ⇒ 5y − 3y = 240 ⇒ 2y = 240 ⇒ y = 120
25.
If the sum of three consecutive numbers is more than the middle number by 130, then the middle number is :
Answer
x + (x + 1) + (x + 2) = (x + 1) + 130 ⇒ 2x + 2 = 130 ⇒ 2x = 128 ⇒ x = 64
∴ Middle number = (x + 1) = 64 + 1 = 65
Answer :
Option BExplanation :
x + (x + 1) + (x + 2) = (x + 1) + 130 ⇒ 2x + 2 = 130 ⇒ 2x = 128 ⇒ x = 64
∴ Middle number = (x + 1) = 64 + 1 = 65
Jump to page number :