31. 320 is how much percentage less than 400?

320, 400 से कितने प्रतिशत कम है?

Option “B” is correct.

The difference between the number = 400 – 320 = 80 

According to the question,

We have to find the percentage with respect to 400 

Required percentage = [(400 – 320)/400] × 100%

∴ The required percentage is 20%

32. A number is first increased by 40% and then it is increased by 30%. What is the net percentage increase?

एक संख्या को पहले 40% बढ़ाया जाता है और फिर इसे 30% बढ़ाया जाता है। कुल प्रतिशत वृद्धि क्या है?

Option “C” is correct.

Net percentage increase = x + y + xy/100

⇒ Net percentage increase = 40 + 30 + 12 = 82%

∴ Net percentage increases is 82%.

33. What is 0.0024% of 0.005?

0.005 का 0.0024% क्या है?

Option “B” is correct.

0.0024% of 0.005

⇒ 0.005 × [0.0024/100]

⇒ 0.0000120/100

⇒ 1.2 × 10-7

34. Rahul increases the price of a commodity by 28% over his purchase rate. He found that nobody is ready to purchase at this price, so he decreases the price by 5% from previous price and sold, then what is profit percent earned by Rahul?

राहुल अपनी खरीद दर से वस्तु की कीमत में 28% की वृद्धि करता है। उसने पाया कि कोई भी इस मूल्य पर खरीद करने के लिए तैयार नहीं है, इसलिए उसने कीमत को पिछली कीमत से 5% कम कर दिया और बेच दिया, फिर राहुल द्वारा अर्जित लाभ प्रतिशत क्या है?


Option “B” is correct.

Let purchased price = 100x

Price after increment = 128% of 100x = 128x

Price of reduction = 95% of 128x = 121.6x

Profit amount = 121.6x – 100x = 21.6x

Profit percent = (21.6x/100x) × 100 = 21.6%

35. If the price of a book first increased by 30% and then decreased by 30%. What is the net change in the price of the book?

यदि किसी किताब की कीमत पहले 30% बढ़ती है और फिर 30% घटती है। पुस्तक की कीमत में शुद्ध परिवर्तन क्या है?

Option “C” is correct.

Let the original price of the book be Rs x

After an increase of 30%, price = x + x × 30/100

⇒ Rs 1.3x

After a decrease of 30%, price = 1.3x – 1.3x × 30/100

⇒ 0.91x

∴ Net decrease in the price of the book,

x0.91x/x×100%

⇒ 9%

36. A scored 72% in a paper with maximum marks of 900 and 80% in another paper with maximum marks of 700. If the result is based on the combined percentage of two papers, the combined percentage is

Option “A” is correct.

Total maximum number of both subjects = 900 + 700 = 1600

A scored in first paper = 900 × (72/100) = 648

A scored in second paper = 700 × (80/100) = 560

Total scored in both subjects = 648 + 560 = 1208

∴ Required percentage = 1208/1600 × 100 = 75.5%

37. A man spends 75% of his income. His income increases by 20% and his expenditure also increases by 10%. Find the percentage increase in his savings.

एक व्यक्ति अपनी आय का 75% व्यय करता है। उसकी आय में 20% की वृद्धि होती है और उसके व्यय में भी 10% की वृद्धि होती है। उसकी बचत में प्रतिशत वृद्धि ज्ञात कीजिए।


Option “B” is correct.

Let the total income of man be Rs. 100

Expenditure of man = 100 × 75/100 = Rs. 75

Savings of income = 100 – 75 = Rs. 25

New income of man = 100 × (120/100) = Rs. 120

New expenditure of man = 75 × (110/100) = 82.5

New savings of man = 120 – 82.5 = 37.5

Savings increased by = 37.5 – 25 = 12.5

Savings increased by (in %) = 12.5/25 × 100 = 50%

38. The value of an article depreciates every year by 10%. If its present value is 50,000 then the value of the article after 2 years is ______

एक वस्तु के मूल्य में प्रतिवर्ष 10% की कमी आती है। यदि इसका वर्तमान मूल्य 50,000 है तो 2 वर्षों के बाद वस्तु का मूल्य ______ होगा। 


Option “D” is correct.

The present value of the article is Rs. 50,000

The article depreciates each year by 10%

Value of the article after two years = P(1 – r/100 )2

= 50000 (1 – 10/100)2

= 40,500

Alternate MethodThe present value of the article is Rs. 50,000

The article depreciates each year by 10%

According to the question, 

50,000 × 90/100 × 90/100 

= 50,000 × 9/10 × 9/10 

= 40,500

39. In a class, 5% students are absent on a particular day. If the number of students present is 38, then total strength of the class on that day is:

एक कक्षा में, किसी विशेष दिन 5% छात्र अनुपस्थित होते हैं। यदि उपस्थित छात्रों की संख्या 38 है, तो उस दिन कक्षा में छात्रों की कुल संख्या कितनी है?

Option “C” is correct.

Let, total strength of the class = 100x

According to the question,

5% of the students absent on the day

Number of students absent

⇒ (5/100) × 100x = 5x

Total number of students present on the day

⇒ 100x – 100x × 5/100 = 38

⇒ 95x = 38

⇒ x = 38/95 = 0.4

∴ Total strength of the class = 100 × 0.4 = 40

40. 28% of 675 is ________.

675 का 28% ________ है।

Option “C” is correct.

Given:

28% of 675

Formula Used:

a% of b = (a/100) × b

Calculation:

⇒ (28/100) × 675 = 0.28 × 675 = 189

∴ Required value is 189

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