Arithmetic Mock Test 1 with Key and Explanations
This is the Sample Mock Test for the Mock Test which are going to commerce from 1st April to 15th April 2016.
Telangana Police SI Mock Tests from 1st to 15th April 2016
 A fruit seller had some apples. He sells 40% apples and still has 420 apples. Originally, he had
Explanation:
Suppose originally he had x apples.
Then, (100 – 40)% of x = 420.

60  x x = 420 
100 
x =  420 x 100  = 700.  
60 
2. The average of 20 numbers is zero. Of them, at the most, how many may be greater than zero?
Explanation:
Average of 20 numbers = 0.
Sum of 20 numbers (0 x 20) = 0.
It is quite possible that 19 of these numbers may be positive and if their sum is a then 20th number is (a).
 A train passes a station platform in 36 seconds and a man standing on the platform in 20 seconds. If the speed of the train is 54 km/hr, what is the length of the platform?
Explanation:
Speed =  54 x  5  m/sec = 15 m/sec.  
18 
Length of the train = (15 x 20)m = 300 m.
Let the length of the platform be x metres.
Then,  x + 300  = 15 
36 
x + 300 = 540
x = 240 m.
 A can lay railway track between two given stations in 16 days and B can do the same job in 12 days. With help of C, they did the job in 4 days only. Then, C alone can do the job in:
Explanation:
(A + B + C)’s 1 day’s work =  1  , 
4 
A’s 1 day’s work =  1  , 
16 
B’s 1 day’s work =  1  . 
12 
C’s 1 day’s work =  1  –  1  +  1  =  1  –  7  =  5  .  
4  16  12  4  48  48 
So, C alone can do the work in  48  = 9  3  days. 
5  5 
 In how many ways can the letters of the word ‘LEADER’ be arranged?
The word ‘LEADER’ contains 6 letters, namely 1L, 2E, 1A, 1D and 1R.
Required number of ways =  6!  = 360. 
(1!)(2!)(1!)(1!)(1!) 
 Square root of 1.5625 = ?
 In what ratio must a grocer mix two varieties of pulses costing Rs. 15 and Rs. 20 per kg respectively so as to get a mixture worth Rs. 16.50 kg?
Explanation:
By the rule of alligation:
Cost of 1 kg pulses of 1^{st} kind Cost of 1 kg pulses of 2^{nd} kind  
Rs. 15  Mean Price Rs. 16.50 
Rs. 20 
3.50  1.50 
 Required rate = 3.50 : 1.50 = 7 : 3.
 A father said to his son, “I was as old as you are at the present at the time of your birth”. If the father’s age is 38 years now, the son’s age five years back was:
Explanation:
Let the son’s present age be x years. Then, (38 – x) = x
2x = 38.
x = 19.
Son’s age 5 years back (19 – 5) = 14 years.
 A clock is started at noon. By 10 minutes past 5, the hour hand has turned through:
Explanation:
Angle traced by hour hand in 12 hrs = 360º.
Angle traced by hour hand in 5 hrs 10 min. i.e.,  31  hrs =  360  x  31  º  = 155º.  
6  12  6 
 How much time will it take for an amount of Rs. 450 to yield Rs. 81 as interest at 4.5% per annum of simple interest?
Explanation:
Time =  100 x 81  years  = 4 years.  
450 x 4.5 