The average weight of 30 students is 45 kg. 15 students whose average weight is 48 kg left the class and 10 students whose average weight is 50 kg joined the class, and then find the new average weight of the students in the class.a45.2b45.4c45.6d45.8
Question
The average weight of 30 students is 45 kg. 15 students whose average weight is 48 kg left the class and 10 students whose average weight is 50 kg joined the class, and then find the new average weight of the students in the class.a45.2b45.4c45.6d45.8
Solution
Sure, let's solve this step by step:
Step 1: Calculate the total weight of the 30 students. The average weight is 45 kg, so the total weight is 30 students * 45 kg/student = 1350 kg.
Step 2: Calculate the total weight of the 15 students who left. Their average weight is 48 kg, so their total weight is 15 students * 48 kg/student = 720 kg.
Step 3: Subtract the total weight of the students who left from the original total weight. This gives 1350 kg - 720 kg = 630 kg.
Step 4: Calculate the total weight of the 10 students who joined. Their average weight is 50 kg, so their total weight is 10 students * 50 kg/student = 500 kg.
Step 5: Add the total weight of the students who joined to the remaining total weight. This gives 630 kg + 500 kg = 1130 kg.
Step 6: Calculate the new average weight. The number of students is now 30 students - 15 students + 10 students = 25 students. So the new average weight is 1130 kg / 25 students = 45.2 kg.
So, the answer is (a) 45.2 kg.
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