Question

15 संख्याओं का औसत 20 है उनमें से पहली 6 संख्याओं का औसत 19 है और अंतिम 7 संख्याओं का औसत 18 है यदि छात्र सातवी संख्या आठवीं संख्या से 2/3 हो तो उन दोनों संख्याओं को बतलाइये ​

Answer 1

Answer:

mean of 15 observation is 20 then sum of all these numbers is equal to 15×20 = 300

And mean of 6 observation is 19 , then sum of these numbers = 19 × 6 = 109

mean of last 7 observation = 18 ,then sum of these numbers = 18×7= 126

so, 7th and 8th observation 's sum is

300-126+109

= 300-235= 65

let 7th observation is x and 8th is y.

And z = x/3

then 65/5 =z

z=13

then x= 13×3=39

and y = 2/3 × x

y = 2/3 × 39

y = 2×13= 25

so, 7th and 8th observation are 26 and 39 respectively.

Step-by-step explanation: