Question

Calculate mean, variance and standard deviation for the following distribution. | Classes | 30-40 | 40-50 | 50-60 | 60-70 | 70-80 | 80-90 | 90-100 | |---------|-------|-------|-------|-------|-------|-------|--------| | Frequency | 3 | 7 | 12 | 15 | 8 | 3 | 2 |

Find the mean, variance and standard deviation using short-cut method | Height in cms | 70-75 | 75-80 | 80-85 | 85-90 | 90-95 | 95-100 | 100-105 | 105-110 | 110-115 | |---------------|-------|-------|-------|-------|-------|--------|---------|---------|---------- | | No. of children | 3 | 4 | 7 | 7 | 15 | 9 | 6 | 6 | 3 |