RPF Constable practice question
The mean of 40 observations was found to be 65. Later it was discovered that an observation 2 was wrongly read as 22. Find the correct mean.
From a RPF Constable Quantitative Aptitude practice set · Quantitative Aptitude
Tap an option to check your answer.
Show answer and explanation
Correct answer: (B) 64.5
Wrong sum = 40 × 65 = 2600. Correct sum = 2600 − 22 + 2 = 2580. Correct mean = 2580/40 = 64.5. (Shortcut: correct mean = 65 + (2 − 22)/40.)
हिंदी में प्रश्न
40 प्रेक्षणों का माध्य 65 पाया गया। बाद में पता चला कि एक प्रेक्षण 2 को गलती से 22 पढ़ लिया गया था। सही माध्य ज्ञात कीजिए।
उत्तर जाँचने के लिए किसी विकल्प पर टैप करें।
उत्तर और व्याख्या देखें
सही उत्तर: (B) 64.5
गलत योग = 40 × 65 = 2600। सही योग = 2600 − 22 + 2 = 2580। सही माध्य = 2580/40 = 64.5। (शॉर्टकट: सही माध्य = 65 + (2 − 22)/40।)
More solved Quantitative Aptitude questions
- In a race of 200 m, the speeds of A and B are in the ratio 12:6. Find by how many meters A beats B.
- The average weight of 25 persons decreases by 1 kg when a person is replaced by a new person weighing 76 kg. Find the weight of the person…
- Find the sum of the first 10 terms of the arithmetic progression 12, 15, 18, ….
- The true discount on a bill is Rs. 1200 and the banker's gain is Rs. 15. Find the banker's discount.
- 10 notebooks cost ₹420. How many notebooks can be bought for ₹588?
- Find the simple interest on ₹13,500 at 6% per annum for 4 years.