Question

The mean of a certain number of items is 20. If an observation 25 is added to the data, the mean becomes 21. Then the number of items in the original data __________.

Answer 1

Answer:

28 answer

Step-by-step explanation:

$Mean of 15 observations = 20</p><p>Sum of 15 observations = 20×15 = 300</p><p>If 8 is added to all the observations,</p><p>Sum of 15 observations = 300+15×8 = 420</p><p>New mean = 15420 = 28</p><p></p><p>$