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Aptitude Simplification Test Yourself

3170.If a - b= 3 and a2 + b2 = 29, find the value of ab.
10
12
15
18
Explanation:

2ab = ($ a $2 + $ b $2) - $\left( a - b \right)$2

   = $\left(29 - 9\right)$ = 20

   $\Rightarrow$ ab= 10.

3171.There are two examinations rooms A and B. If 10 students are sent from A to B, then the number of students in each room is the same. If 20 candidates are sent from B to A, then the number of students in A is double the number of students in B. The number of students in room A is:
20
80
100
200
Explanation:

Let the number of students in rooms A and B be $ x $ and $ y $ respectively.

Then, $ x $ - 10 = $y $ + 10   $\Rightarrow$   $ x $ - $ y $ = 20 .... (i)

     and $ x $ + 20 = 2$\left( y - 20\right)$   $\Rightarrow$   $ x $ - 2$ y $ = -60 .... (ii)

Solving (i) and (ii) we get: $ x $ = 100 , $ y $ = 80.

$\therefore$ The required answer A = 100.

3172.In a regular week, there are 5 working days and for each day, the working hours are 8. A man gets Rs. 2.40 per hour for regular work and Rs. 3.20 per hours for overtime. If he earns Rs. 432 in 4 weeks, then how many hours does he work for ?
160
175
180
195
Explanation:

Suppose the man works overtime for $ x $ hours.

Now, working hours in 4 weeks = $\left(5 \times 8 \times 4\right)$ = 160.

$\therefore$ 160 x 2.40 + $ x $ x 3.20 = 432

$\Rightarrow$ 3.20$ x $ = $\left(432 - 384\right)$ = 48

$\Rightarrow x $ = 15.

Hence, total hours of work = $\left(160 + 15\right)$ = 175.

3173.8 / 4 / 2 = ?
4
1
0
2
Explanation:

8 / 4 / 2 = (8 / 4) / 2 = 2/2 = 1

3174.A boy was asked to multiply a number by 22. He instead multiplied the number by 44 and got the answer 308 more than the correct answer. What was the number to be multiplied?
16
10
14
12
Explanation:

Let the number be x

22x + 308 = 44x

=> 44x - 22x = 308

=> 22x = 308

=> x = 308/22 = 154/11 = 14

3175.If a - b = 6 and a2 + b2 = 116, then what is the value of ab?
20
40
60
80
Explanation:

$(a - b)^2 = a^2 - 2ab + b^2$

=> (a - b)2 = a2 - 2ab + b2

=> 62 = 116 - 2ab

=> 36 = 116 - 2ab

=> 2ab = 116 - 36 = 80

=> ab = 40

3176.How many pieces of 85 cm length can be cut from a rod of 42.5 meters long?
15
20
2
50
Explanation:

$\text{Number of pieces = }\dfrac{4250}{85} = \dfrac{850}{17} = 50$

3177.In an examination, a student scores 4 marks for every correct answer and loses 1 mark for every wrong answer. If he attempts all 80 questions and secures 120 marks, How many questions does he answer correctly?
30
60
50
40
Explanation:

Let the number of correct answers be x

Then, number of wrong answers = $\left(80 - x\right)$

4x – $\left(80 - x\right)$ = 120

=> 4x – 80 + x = 120

=> 5x = 200

=> x = 200/5 = 40

i.e., he does 40 questions correctly

3178.A sum of Rs. 1360 has been divided among A, B and C such that A gets $ \dfrac{2}{3} $ of what B gets and B gets $ \dfrac{1}{4} $ of what C gets. Bs share is:
Rs. 120
Rs. 160
Rs. 240
Rs. 300
Explanation:

Let Cs share = Rs. $ x $

Then, Bs share = Rs.$ \dfrac{x}{4} $,   As share = Rs. $\left(\dfrac{2}{3}\times\dfrac{x}{4}\right)$=Rs.$\dfrac{x}{6}$

$\therefore \dfrac{x}{6} $+$ \dfrac{x}{4} $+ $ x $ = 1360

$\Rightarrow \dfrac{17x}{12} $= 1360

$\Rightarrow x $ =$ \dfrac{1360 \times 12}{17} $= Rs. 960

Hence, Bs share = Rs.$ \left(\dfrac{960}{4} \right) $= Rs. 240.

3179.In a garden, 26 trees are planted at equal distances along a yard 300 metres long, one tree being at each end of the yard. What is the distance between two consecutive trees?
10
20
14
12
Explanation:

26 trees have 25 gaps between them.

Length of each gap = 300/25 = 12

i.e., distance between two consecutive trees = 12

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