Question

why the only final good and services included in GDP​

Answer 1

Only final goods and services are counted, to avoid multiple counting, since their prices covers the cost of all intermediate products and services that were used to produce the final output. Another way to calculate GDP is to measure the value added to each product or service at each stage of its production.

Answer 2

Answer:

ᴏɴʟʏ ғɪɴᴀʟ ɢᴏᴏᴅs ᴀɴᴅ sᴇʀᴠɪᴄᴇs ᴀʀᴇ ᴄᴏᴜɴᴛᴇᴅ, ᴛᴏ ᴀᴠᴏɪᴅ ᴍᴜʟᴛɪᴘʟᴇ ᴄᴏᴜɴᴛɪɴɢ, sɪɴᴄᴇ ᴛʜᴇɪʀ ᴘʀɪᴄᴇs ᴄᴏᴠᴇʀs ᴛʜᴇ ᴄᴏsᴛ ᴏғ ᴀʟʟ ɪɴᴛᴇʀᴍᴇᴅɪᴀᴛᴇ ᴘʀᴏᴅᴜᴄᴛs ᴀɴᴅ sᴇʀᴠɪᴄᴇs ᴛʜᴀᴛ ᴡᴇʀᴇ ᴜsᴇᴅ ᴛᴏ ᴘʀᴏᴅᴜᴄᴇ ᴛʜᴇ ғɪɴᴀʟ ᴏᴜᴛᴘᴜᴛ. ᴀɴᴏᴛʜᴇʀ ᴡᴀʏ ᴛᴏ ᴄᴀʟᴄᴜʟᴀᴛᴇ ɢᴅᴘ ɪs ᴛᴏ ᴍᴇᴀsᴜʀᴇ ᴛʜᴇ ᴠᴀʟᴜᴇ ᴀᴅᴅᴇᴅ ᴛᴏ ᴇᴀᴄʜ ᴘʀᴏᴅᴜᴄᴛ ᴏʀ sᴇʀᴠɪᴄᴇ ᴀᴛ ᴇᴀᴄʜ sᴛᴀɢᴇ ᴏғ ɪᴛs ᴘʀᴏᴅᴜᴄᴛɪᴏɴ.