Question

the average of 21 numbers is 36. if the average of first 12 numbers is 15. find the average of last 9 numbers?​

Answer 1

Answer:

ᴠɪsᴜᴀʟɪsᴇ ᴀᴠᴇʀᴀɢᴇ ᴀs ᴄᴏɴᴄᴇᴘᴛ ᴏғ “ɢɪᴠᴇ & ᴛᴀᴋᴇ”.

ᴀᴠᴇʀᴀɢᴇ ᴏғ ғɪʀsᴛ 8 ɴᴜᴍʙᴇʀ = 21

ᴀᴠᴇʀᴀɢᴇ ᴏғ ʟᴀsᴛ 4 ɴᴜᴍʙᴇʀ = 18

ɪғ ᴀᴠᴇʀᴀɢᴇ ᴏғ ᴀʟʟ 12 ɴᴜᴍʙᴇʀs ɪs 18, ᴛʜᴇɴ ᴡᴇ ʜᴀᴠᴇ 8 x 3 = 24 ᴇxᴛʀᴀ ғʀᴏᴍ ғɪʀsᴛ ᴇɪɢʜᴛ ɴᴜᴍʙᴇʀs.

ᴛʜɪs ᴇxᴛʀᴀ ɪs ᴅɪsᴛʀɪʙᴜᴛᴇᴅ ᴏᴠᴇʀ ᴀʟʟ 12 ɴᴜᴍʙᴇʀs ɪɴᴄʀᴇᴀsɪɴɢ ᴛʜᴇɪʀ ᴀᴠᴇʀᴀɢᴇ ʙʏ 24/12 = 2.

=> ғɪɴᴀʟ ᴀᴠᴇʀᴀɢᴇ = 18 + 2 = 20

ɴᴏ ᴇϙᴜᴀᴛɪᴏɴs ɴᴏ ғᴜss.

ɴᴏᴛᴇ : ᴛʜɪs ᴍᴇᴛʜᴏᴅ ɪs ғᴏʀ ᴀᴘᴛɪᴛᴜᴅᴇ ᴛᴇsᴛ ᴛᴀᴋᴇʀs ᴀɴᴅ ɴᴏᴛ ғᴏʀ sᴄʜᴏᴏʟ ʜᴏᴍᴇᴡᴏʀᴋ.

:-)