Question

Find the mean and standard deviation using short-cut method. | xi | 60 | 61 | 62 | 63 | 64 | 65 | 66 | 67 | 68 | |----|----|----|----|----|----|----|----|----|----| | fi | 2 | 1 | 12 | 29 | 25 | 12 | 10 | 4 | 5 |

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 |