Multiple choice

The average weight of the students in a group was 75.4 kg. Later on, four students having weights, 72.9 kg. 73.8 kg, 79.5 kg and 87.4 kg joined the group. As a result, the average weight of all the students in the group increased by 0.24 kg. What was the number of students in the group, initially? एक समूह में विद्यार्थियों का औसत भार 75.4 किग्रा था। बाद में, चार छात्र जिनका वजन 72.9 किग्रा 73.8 किग्रा, 79.5 किग्रा और 87.4 किग्रा समूह में शामिल हुए। परिणामस्वरूप, समूह के सभी विद्यार्थियों के औसत भार में 0.24 किग्रा की वृद्धि हुई। प्रारंभ में समूह में विद्यार्थियों की संख्या कितनी थी?

  1. 44

  2. 46

  3. 50

  4. 52

  5. None of these इनमें से कोई नहीं

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let initial students = n. Total initial weight = 75.4n kg. Four students join with total weight = 72.9 + 73.8 + 79.5 + 87.4 = 313.6 kg. New total = 75.4n + 313.6 kg for (n + 4) students. New average = 75.4 + 0.24 = 75.64 kg. Therefore: (75.4n + 313.6)/(n + 4) = 75.64. Solving: 75.4n + 313.6 = 75.64n + 302.56. 313.6 - 302.56 = 75.64n - 75.4n. 11.04 = 0.24n. n = 11.04/0.24 = 46 students.