A retailer buy tokla tea at rs 525 per kg and mixed with soktim tea bought at rs 750 per kg .in what proportion should he mix two kinds of tea so as to make a profi 5% on selling the mixture at Rs 700 per kg .

Scores on the cognitive scale of the bayley-scales of infant and toddler development range from 1 to 19, with a standard deviation of 3. calculate the margin of error in estimating the true mean cognitive scale score, with 99% confidence, if there are 12 infants and toddlers in a sample.