1. Find the average of the first 20 natural numbers?

A. 10 B. 11.5 C. 12 D. 10.5

Answer: Option D
Explanation: Average of the first 'n' natural numbers = (n + 1)/2 We get [latex]\frac {(20 + 1)}{2}[/latex] = 10.5
2. The average of 13 numbers is 60. Average of the first 7 of them is 57 and that of the last 7 is 61. Find the 8th number?

A. 46 B. 32 C. 68 D. 51

Answer: Option A
Explanation: Sum of all the 13 numbers = 13 * 60 = 780 Sum of the first 7 of them = 7 * 57 = 399 Sum of the last 7 of them = 7 * 61 = 427 So, the 8th number = 427 + 399 - 780 = 46.
3. A batsman makes a score of 64 runs in the 16th innings and thus increased his average by 3. Find his average after the 16th inning?

A. 17 B. 29 C. 18 D. 19

Answer: Option D
Explanation: Let the average after the 16th inning be P. So, the average after the 15th inning will be (P-3) Hence, 15(P-30) + 64 = 16P => P = 19
4. The average marks of a class of 30 students is 40 and that of another class of 50 students is 60. Find the average marks of all the students?

A. 50 B. 47.5 C. 59 D. 52.5

Answer: Option D
Explanation: ∵Let after x hours the second train will meet the first train. Sum of the marks for the class of 30 students = 30 * 40 = 1200 Sum of the marks for the class of 50 students = 50 * 60 = 3000 Sum of the marks for the class of 80 students = 1200 + 3000 = 4200 Average marks of all the students = [latex]\frac {4200}{80}[/latex] = 52.5
5. The average salary of a person for the months of January, February, March and April is Rs.8000 and that for the months February, March, April and May is Rs.8500. If his salary for the month of May is Rs.6500, find his salary for the month of January?

A. 3000 B. 2500 C. 4500 D. 5000

Answer: Option C
Explanation: Sum of the salaries of the person for the months of January, February, March and April = 4 * 8000 = 32000 ----(1) Sum of the salaries of the person for the months of February, March, April and May = 4 * 8500 = 34000 ----(2) (2)-(1) i.e. May - Jan = 2000 Salary of May is Rs.6500 Salary of January = Rs.4500

1. A candidate who gets 30% of the marks fails by 50 marks. But another candidate who gets 45% marks gets 25 marks more than necessary for passing. Find the number of marks for passing?

A. 150 B. 200 C. 250 D. 275

Answer: Option B
Explanation: 30% ------------ 50 45% ------------ 25 ---------------------- 15% ------------- 75 30% -------------- ? 150 + 50 = 200 Marks
2. After 38 liters of petrol were poured into the tank, it was still 5% empty. How much petrol must be poured into the tank in order to fill it?

A. 38 liters B. 40 liters C. 38.5 liters D. 2 liters

Answer: Option D
Explanation: 95% ----------- 38 5% ------------ ? => 2 liters
3. The population of a town is 45000; 5/9th of them are males and the rest females 40% of the males are married. What is the percentage of married females?

A. 60% B. 50% C. 45% D. 40%

Answer: Option B
Explanation: Male = 45,000* [latex]\frac {5}{9}[/latex] = 25,000 Female = 45,000* [latex]\frac {4}{9}[/latex] = 20,000 Married Male = 25,000* [latex]\frac {40}{100}[/latex] = 10,000 Married Female = 10,000 20,000 ------------ 10,000 100 ------------- ? => 50%
4. The salary of a worker is first increased by 30% and afterwards reduced by 30%. What is net change in his salary?

A. 90% increase B. 45% increase C. 9% decrease D. Same as before

Answer: Option C
Explanation: [latex]\frac {(30 * 30)}{100}[/latex] = 9% decrease
5. A person spends 1/5th of his income on the education of his children, and 20% of the remaining on food. If he is left with Rs.576 find his income?

A. Rs.900 B. Rs.800 C. Rs.500 D. Rs.1000

Answer: Option A
Explanation: X *[latex]\frac {4}{5}[/latex] *[latex]\frac {80}{100}[/latex] = 576 X = 14400/16 X = 900