SBI PO Prelims 2021: How to Approach Quantitative Aptitude [ with Sample Questions]

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The SBI PO Prelims exam 2021 has been scheduled to be held on November 20, 21 & 27, 2021. In these last few days, we hope you are practicing more and more sample questions every day. In this article, we have put together some tricks and tips that you can use as you prepare for your exam. We have also curated a list of solved and unsolved questions from a number of topics that you can take help from to understand the kind of questions you may expect.

Important Points to Remember

For the SBI PO Prelims exam, out of 35 questions, 23-24 questions will be asked from the below mentioned first 4 topics. The remaining questions will be from Arithmetic Word Problems.

TopicLevel of AssessmentNo. of Question
Data InterpretationEasy to Moderate10-15
Quadratic EquationsEasy5
Number SeriesEasy 5
Simplification/ApproximationEasy 5
Arithmetic Word Problems (Time & Work, Percentage and such) Easy to Moderate11-12 

Some calculation tricks that you must know if you are appearing for the SBI PO exam are provided below. These tricks will definitely help you in increasing your speed and you will be able to attempt more questions in the exam. 

Trick #1 

Square of the numbers ending with 5.

We can find the Square of any number whose last digit is 5.

Just write 25 in the end & multiply the digit ahead of 5 to its next place & put the product before 25. Simply you will get the final answer

It means, n52 = n(n+1)/25

So, 452 = 4×5/25 = 2025

552 = 5×6/25 = 3025

652 = 6×7/25 = 4225

1052 = 10×11/25 = 11025

Trick #2 

Square of numbers near to 50.

If the number is more than 50, then

(50+n)2 = (25+n)/n2

In the end n2 must have only 2 digits. If it has only 1 digit like 32 =9, we will write it as 09.

If it has 3 digits like 122 = 144 then write 44 in the end only & carry 1 in (25+n)

It means 532 = (50+3)2 = 25+3/32 = 2809

522 = (50+2)2 = 25+2/22 = 2704

562 = (50+6)2 = 25+6/62 = 3136

622 = (50+12)2 = 25+12/122 = 37/144 = 37+1/44 = 3844

642 = (50+14)2 = 25+14/142 = 39/196 = 39+1/96 = 4096

If the number is less than 50, then

(50-n)2 = (25-n)/n2

In the end n2 must have only 2 digits. If it has only 1 digit like 32 =9, we will write it as 09.

If it has 3 digits like 122 = 144 then write 44 in the end only & carry 1 in (25+n)

It means 472 = (50-3)2 = 25-3/32 = 2209

482 = (50-2)2 = 25-2/22 = 2304

442 = (50-6)2 = 25-6/62 = 1936

382 = (50-12)2 = 25-12/122 = 13/144 = 13+1/44 = 1444

362 = (50-14)2 = 25-14/142 = 11/196 = 11+1/96 = 1296

Trick #3

Square of numbers near to 100.

If the number is more than 100, then

(100+n)2 = (100+n+n)/n2

In the end n2 must have only 2 digits. If it has only 1 digit like 32 =9, we will write it as 09.

If it has 3 digits like 122 = 144 then write 44 in the end only & carry 1 in (100+n+n)

It means 1032 = (100+3)2 =100+3+3/32 = 10609

1022 = (100+2)2 =100+2+2/22 = 10404

1062 = (100+6)2 =100+6+6/62 = 11236

1122 = (100+12)2 = 100+12+12/122 = 124/144 = 124+1/44 = 12544

1142 = (100+14)2 = 100+14+14/142 = 128/196 = 128+1/96 = 12996

If the number is less than 100, then

(100-n)2 = (100-n-n)/n2

In the end n2 must have only 2 digits. If it has only 1 digit like 32 =9, we will write it as 09.

If it has 3 digits like 122 = 144 then write 44 in the end only & carry 1 in (100-n-n)

It means 972 = (100-3)2 =100-3-3/32 = 9409

982 = (100-2)2 =100-2-2/22 =9604

942 = (100-6)2 =100-6-6/62 = 8836

882 = (100-12)2 = 100-12-12/122 = 76/144 = 76+1/44 = 7744

862 = (100-14)2 = 100-14-14/142 = 72/196 = 72+1/96 = 7396

Some Other Tips

  1. Memorize squares upto 50 (minimum 30)
  2. Memorize cubes upto 20
  3. Memorize multiplication tables upto 20
  4. Percentage to fraction conversion and vice versa
  5. Practice DI/Simplification/Approximation/Number Series and Quadratic equations problems every day. 

How to Approach Quantitative Aptitude section.

  1. Try to solve the easy problems first and then gradually move to the Moderate/Difficult ones. 
  2. In continuation with the last point, attempt questions from Approximation/ Simplification, Quadratic Equations and Number Series first as these take comparatively lesser time. 
  3. Don’t spend undue time on analyzing the pattern of the number series, just give it a quick read and if you get the pattern go ahead, otherwise skip and move to next.
  4. Attempt DI only if you have practiced well. If you haven’t practiced enough, try to solve the rest of the questions first and then move into this section as it can be quite time-consuming.  
  5. Don’t spend too much time on one question. If you don’t know the answer, move on to the next. 
  6. Accuracy is key. While it is important to answer as many questions as you can, it is imperative that you answer these questions correctly to score marks. 

Solved Sample Questions

In this section, we have compiled some solved examples for your perusal. Take a look at them below. 

  1. What will come in place of the question mark (?) in the following series?

8, 17, 36, 75, ?, 313

Solution: 

8 × 2 + 1 = 17

17 × 2 + 2 = 36

36 × 2 + 3 = 75

75 × 2 + 4 = 154

154 × 2 + 5 = 313

Answer: 154

  1.  ‘n’ men working 18 hours a day can complete a work in 24 days while (5n – 4) men working 12 hours a day can complete the same work in 9 days. In how many days can (n + 4) men working 6 hours a day complete the same work?

Solution:

According to the question,

(n × 18 × 24) = {(5n – 4) × 12 × 9}

Or, 4n = 5n – 4

Or, n = 4

Let the number of days taken by (n + 4) = 8 men be ‘x’ days

Therefore,

(8 × 18 × 24) = (8 × 6 × x)

Therefore, x = 72 days

Answer: 72 days

  1.  A man invested Rs. 2x and Rs. 4x at 10% simple interest and at 5% compound interest (compounded annually) for two years respectively. Difference between simple interest and compound interest received after two years is Rs.680. Find the value of x.

Solution: 

According to the question,

=> [4x (1.05)2 – 4x] – (2x × 10 × 2)/100 = 680

=> [4.41x – 4x] – (4x/10) = 680

=> 0.1x = 6800

=> x = Rs. 68000

Answer: Rs 68,000

  1.  Average of present ages of A and B is 30 years. Ratio of age of A to age of B, after 10 years will be 7:9, respectively. What will be the ratio of their ages 5 years ago?

Solution: 

Let, present age of A is ‘x’ years

Present age of B = 30 × 2 – x = ‘60 – x’ years

According to question;

(x + 10)/(60 – x + 10) = 7/9

Or, 9x + 90 = 490 – 7x

Or, 16x = 400

Or, x = 25

Desired ratio = (25 – 5) :(60 – 25 – 5) = 20:30 = 2:3

Answer: 2:3

Sample Question for Practice

We have provided a list of questions from a variety of topics for your practice. Test yourselves on these topics and let us know how you fared. 

Q1. Answer the questions based on the information given below.

The cost of per click per person for a website page is different for different days. The table given below shows the total amount of money collected from a website on different days of a week and average price of a per click on the respective days. The table also shows the ratio of number of males to female visitors to the website on different days of a week.

DaysTotal amount collectedAverage cost of per click per personRatio of number of male visitors to female visitors
Monday7800159:4
Tuesday8640207:5
Wednesday14000253:2
Thursday8100185:4
Friday21600308:7

Qi. What is the average number of visitors to the website on Monday, Wednesday and Friday together?

(a) 600

(b) 650

(c) 750

(d) 850

(e) none of these

Qii. Total number of visitors on Saturday is 40% more than the same on Thursday while the number of male visitors on Saturday is 48% more than the same on Thursday. Find the number of female visitors to the website on Saturday.

(a) 260

(b) 200

(c) 250

(d) 230

(e) none of these

Qiii. 45%, 60% and 62.5% of the females who visited the website on Monday, Tuesday and Wednesday respectively. Find the number of female visitors who visited the website in these three days.

(a) 360

(b) 320

(c) 200

(d) 330

(e) none of these

Q2. A, B and C started a business by investing Rs. a, Rs. a + 4000 and Rs. a + 9000 respectively. After 6 months, A withdraws Rs. 1000. And after another 2 months, B invested Rs. 2500 more. Find the value of a, if the share of A, B and C at the end of the year is in the ratio of 33: 65: 90? 

(a) 12000

(b) 1500

(c) 1800

(d) 1650

(e) 1850

Q3. In three cities A, B and C, the total number of cars (electric and non-electric) are in the ratio 9:8:3. In A, 80% of the cars are non-electric, in B, 30% of the people are electric. If 90% of cars in city C are non-electric. Find the percentage of non-electric cars in these three cities.

(a) 66.5%

(b) 77.5%

(c) 55.5%

(d) 60.5%

(e) 65.75%

Q4. What will come in place of the question mark (?) in the following series?

12, 31, 48, ?, 72, 79

(a) 62

(b) 65

(c) 61

(d) 70

(e) 60

Q5. A invested a sum at a certain rate of interest on simple interest and he got 90% more amount after 4 years. If he invests Rs. 7200 at the same rate of interest on SI, then find the total interest he would get after 5 years?

(a) 12000

(b) 15000

(c) 8100

(d) 6650

(e) 8850

Q6. The speed of current is 12 km/h. What will be the respective downstream speed and upstream speed of a boy rowing a boat, if one fifth of the distance covered going downstream in a certain time is equal to the distance covered going upstream in the same time?

(a) 30 km/h, 8 km/hr

(b) 30 km/h, 6 km/hr

(c) 32 km/h, 6 km/hr

(d) 30 km/h, 9 km/hr

(e) 35 km/h, 6 km/hr

Q7. What will come in the place of the question mark (?) in the given expression?

21% of 4200 – 42% of 2100 + 12 × 5 = ?% of 240

(a) 20

(b) 25

(c) 26

(d) 33

(e) 28

Want the answer key? Comment your answers below and we will get back to you with the correct answers. 

We hope these sample questions help you in your preparation. If you want to practice more questions, it would be a good idea to take an SBI PO Prelims free mock test with ixamBee.  In this way, you will be able to evaluate the kind of questions asked in all subjects and not only Quantitative Aptitude. 

There are 5 free mock tests available at ixamBee! Take one now!

Also take a look at SBI PO Prelims Previous Year Papers as well

If you need any other clarification or any sort of assistance, please feel free to reach out to us. 

All the best! 

Also read

SBI PO 2021 Admit Card [Out]: Direct Link for Download

SBI PO 2021 Syllabus: Find the Complete Syllabus Here

SBI PO Exam Analysis 2020

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