what is ui in statistics class 10

In statistics class 10, "ui" refers to a new variable obtained from variable "Xi" by subtracting the assumed mean "M" and dividing the result by the class width "H". This is part of the step deviation method, which is used to calculate the mean of a distribution when the data is given in grouped form. The step deviation method involves finding the class mark for each class interval, subtracting the assumed mean from each class mark to get the deviation, and then dividing each deviation by the class width to get the "ui" value for each class interval. The mean can then be calculated using the formula x = a + (Σfiui)/Σfi, where "a" is the assumed mean.