#### A grouped frequency distribution table with class intervals of equal size ………… 250 270 (270 not included in this interval) as one of the class intervals is constructed for the following data:

268, 220, 368, 258, 242, 310, 272, 342, 310, 290, 300, 320, 319, 304, 402, 318, 406 ………..

(a) 4

(b) 5

(c) 6

(d) 7

**Solution:**

(c) 6 is correct

#### The mean of x- 1, x + 1, x + 3 and x + 5 is…….

**Solution:**

(b) x + 2

#### The mean of five numbers is 30. If one number is excluded, their mean ….. The excluded number is……

**Solution:**

Let a,b,c,d and e are five numbers

mean = (a +b+ c+ d+e)/5 = 30

⇒ (a +b+ c+ d+e) = 150_______(1)

now, Let the number excluded be a

then, new mean = (b+ c+ d+e)/4 = 28

⇒ (b+ c+ d+e)= 112

putting this value in (1),

⇒a + 112 = 150

⇒a = 150 -112 = 38

∴ excluded number = 38 is correct

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