A group of 210 students appeared in some test. The mean of 1÷3rd of students is found to be 60.The mean of the remaining students is found to be 78. Then what is the mean of the whole group
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Total = 210
Mean of 1/3 ie. 70 = 60
Mean of 2/3 ie. 140 = 78
Total of 70 students = 60 × 70= 4200
Total of 140 students = 140 × 78 = 10920
Total of 210 students = 10920 + 4200= 15120
Mean of 210 students = 15120 ÷ 210 = 72
Mean of 1/3 ie. 70 = 60
Mean of 2/3 ie. 140 = 78
Total of 70 students = 60 × 70= 4200
Total of 140 students = 140 × 78 = 10920
Total of 210 students = 10920 + 4200= 15120
Mean of 210 students = 15120 ÷ 210 = 72
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