# Elementary Statistics – RRB JE Mock Test Series for ECE PDF

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Statistics have shown to be a beneficial instrument in practically all disciplines of work throughout the globe. Statistics could be found in various fields, including study, teaching, economics, government, psychiatry, and even the most basic occurrence that requires study. According to the New Encyclopaedia Britannica, statistics seems to be the art and science of acquiring, interpreting, and drawing conclusions from the results.

It’s proven beneficial for keeping track of information regarding individuals, items, and incidents and generating predictions based on the evidence presented. Data is an essential instrument for getting views from a survey in today’s world. These viewpoints frequently have impacted citizens, assisting them in anticipating future responses or activities. In the instance of a firm, for reference, if a study reveals unfavourable feedback from customers, the firm of a specific product might improve advertising, product quality, or cost.

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**Elementary Statistics | RRB JE Mock Test Series for ECE**

**Information about Elementary Statistics - RRB JE Mock Test Series for ECE | Railways | Notes, Videos & Tests**

In this chapter you can find the Elementary Statistics - RRB JE Mock Test Series for ECE | Railways | Notes, Videos & Tests defined & explained in the simplest way possible. Besides explaining types of Elementary Statistics - RRB JE Mock Test Series for ECE | Railways | Notes, Videos & Tests theory, EduRev gives you an ample number of questions to practice Elementary Statistics - RRB JE Mock Test Series for ECE | Railways | Notes, Videos & Tests tests, examples and also practice Railways tests.

**Examples Of Elementary Statistics:**

**Q1. What is the average (arithmetic mean) of 5, 10, 15, 20, 25, 30, 35, 40, 45, 50**

**5, 10, 15, 20, 25, 30, 35, 40, 45, 50 का औसत (अंकगणितीय माध्य) क्या है?**

(a) 55

(b) 45

(c) 35

(d) 27.5

S1. Ans.(d)

Sol.

Clearly, it’s an A.P. with common difference = 5

First term = 5 & Last term = 50

So, sum = n/2(a+l)

And, mean =(n/2(a+l))/n=(a+l)/2=(5+50)/2=27.5

**Q2. The arithmetic mean of the length of 100 equivalent cars is d metres. Then, which of the following is the total length (in metes) of all the cars in term of d?**

**100 समतुल्य कारों की लंबाई का अंकगणित औसत d मीटर है. फिर, निम्नलिखित में से कौन सी d के टर्म में सभी कारों की कुल लंबाई (मीटर में) है?**

(a) d + 100

(b) 100 -d

(c) d/100

(d) 100d

S2. Ans.(d)

Sol.

Clearly (sum of length of 100 equivalent cars)/100=d

⇒sum of length of 100 equivalent cars=100d

**Q3. What is the mean of 0, 1, 0, 9, 6, 14, 0, 10, 20**

**0, 1, 0, 9, 6, 14, 0, 10, 20 का औसत क्या है?**

(a) 8.88

(b) 6.66

(c) 2.22

(d) 4.44

S3. Ans.(b)

Sol.

mean=(0+1+0+9+6+14+0+10+20)/9

=60/9=6.66

**Q4. Find the arithmetic mean of following:**

**निम्नलिखित का अंकगणितीय औसत ज्ञात कीजिए**

**x, x+1, x+2, x+3, x+4**

(a) x +2

(b) 5x +10

(c) (2x+5)/2

(d) (2x+5)/3

S4. Ans.(a)

Sol.

Mean of n consecutive numbers=(n+1)/2 th term …..where n = odd

Here n = 5,

∴mean=(5+1)/2=3rd term = x+ 2

**Q5. Evaluate the following for given set of numbers:**

**दी गई संख्याओं के सेट के लिए निम्नलिखित का मूल्यांकन करें**

**3 × mean + 2 × mode – 6 median**

**Set={1, 2, 2, 3, 3, 3, 4, 4, 4, 4}**

(a) 0

(b) 1

(c) –1

(d) 2

S5. Ans.(c)

Sol.

As we know that mode of a given set of numbers is the observation or number which occurs most frequently.

Clearly numbers are arranged in ascending order

So, mode = 4

median=(3+3)/2=3

mean=30/10=3

So,

3 mean + 2 × mode – 6 median

= 3 × 3 + 2 × 4 – 6 × 3

= 9 + 8 – 18

= 17 – 18 = -1

**Q6. Find mean of first five prime nos.**

**पहले पाँच अभाज्य संख्याओं का औसत ज्ञात कीजिए**

(a) 5.6

(b) 3.6

(c) 5.4

(d) 4.5

S6. Ans.(a)

Sol.

First five prime numbers are 2, 3, 5, 7, 11

mean=(2+3+5+7+11)/5

=28/5=5.6

**Q7. Runs scored by Virat Kohli in some 3 **test** Matches against Australia are as follows 101, 126, 32, 38, 52, and 40. Find median of the given scores.**

**ऑस्ट्रेलिया के खिलाफ 3 टेस्ट मैचों में विराट कोहली द्वारा बनाए गए रन 101, 126, 32, 38, 52 और 40 हैं। दिए गए स्कोर का मीडियन ज्ञात करें.**

(a) 48

(b) 46.5

(c) 46

(d) 47

S7. Ans.(c)

Sol.

Arranging in ascending order

32,38,40,52,101,126

Median = 1/2 [n/2+(n+2)/2]th term..for n = even

⇒Median= (40+52)/2=92/2=46

**Q8. The numbers of rupee notes of different denominations are given as below.**

**विभिन्न मूल्यवर्ग के रुपए के नोटों की संख्या नीचे दी गई है।**

**Denomination 10 20 5**

**Number of notes 15 20 8**

**Find mode of above data**

**उपरोक्त डेटा का मोड ज्ञात करें**

(a) 10

(b) 8

(c) 20

(d) 15

S8. Ans.(c)

Sol.

Clearly ‘20’ is repeated twice so, mode = 20

**Q9. The heights of Arun’s family members are given in cms as 165, 180, 181, 163, 172, 180, 162 The median height of the family will be**

**अरुण के परिवार के सदस्यों की ऊँचाई 165, 180, 181, 163, 172, 180, 162 के रूप में सेमी में दी गई है. परिवार की मीडियन ऊंचाई ज्ञात करें.**

(a) 180

(b) 170

(c) 131

(d) 172

S9. Ans.(d)

Sol.

Arranging heights in ascending order

162, 163, 165, 172, 180, 180, 181

Median = (n+1)/2 th term for n=odd

Hence median = 172 (4th term)

**Q10. Find mode of the following.**

**निम्नलिखित का मोड ज्ञात करें**

**2³, x, y, z, x², x³, y³, z³, x², ax², x², **xy**, bx³, zx³, x², x²y, ax², **xy**, bx³, x³, x²y**

(a) ax²

(b) x²

(c) zx³

(d) bx³

S10. Ans.(b)

Sol.

Clearly, x² is repeated four times

So, mode = x²

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