ᴀ ʀᴏᴄᴋ ꜱᴀᴍᴘʟᴇ ᴄᴏɴᴛᴀɪɴꜱ ᴀ ʀᴀᴅɪᴏᴀᴄᴛɪᴠᴇ ɪꜱᴏᴛᴏᴘᴇ ᴛʜᴀᴛ ʜᴀꜱ ᴀ ʜᴀʟꜰ-ʟɪꜰᴇ ᴏꜰ ₁₀,₀₀₀ ʏᴇᴀʀꜱ. ᴏɴᴇ- ꜰᴏᴜʀᴛʜ (₂₅%) ᴏꜰ ᴛʜᴇ ᴘᴀʀᴇɴᴛ ɪꜱᴏᴛᴏᴘᴇ ʀᴇᴍᴀɪɴꜱ ɪɴ ᴀ ꜱᴀᴍᴘʟᴇ. ʜᴏᴡ ᴏʟᴅ ɪꜱ ᴛʜᴇ ꜱᴀᴍᴘʟᴇ?
ᴀᴄᴛɪᴠɪᴛʏ ₈: ᴀʙꜱᴏʟᴜᴛᴇ ᴅᴀᴛɪɴɢ
ᴅɪʀᴇᴄᴛɪᴏɴꜱ: ꜱᴏʟᴠᴇ ꜰᴏʀ ᴛʜᴇ ꜰᴏʟʟᴏᴡɪɴɢ.
₁. ᴀ ʀᴏᴄᴋ ꜱᴀᴍᴘʟᴇ ᴄᴏɴᴛᴀɪɴꜱ ᴀ ʀᴀᴅɪᴏᴀᴄᴛɪᴠᴇ ɪꜱᴏᴛᴏᴘᴇ ᴛʜᴀᴛ ʜᴀꜱ ᴀ ʜᴀʟꜰ-ʟɪꜰᴇ ᴏꜰ ₁₀,₀₀₀ ʏᴇᴀʀꜱ. ᴏɴᴇ-
ꜰᴏᴜʀᴛʜ (₂₅%) ᴏꜰ ᴛʜᴇ ᴘᴀʀᴇɴᴛ ɪꜱᴏᴛᴏᴘᴇ ʀᴇᴍᴀɪɴꜱ ɪɴ ᴀ ꜱᴀᴍᴘʟᴇ. ʜᴏᴡ ᴏʟᴅ ɪꜱ ᴛʜᴇ ꜱᴀᴍᴘʟᴇ?
₂. ᴀ ʀᴏᴄᴋ ꜱᴀᴍᴘʟᴇ ᴄᴏɴᴛᴀɪɴꜱ ᴀ ʀᴀᴅɪᴏᴀᴄᴛɪᴠᴇ ɪꜱᴏᴛᴏᴘᴇ ᴛʜᴀᴛ ʜᴀꜱ ᴀ ʜᴀʟꜰ-ʟɪꜰᴇ ᴏꜰ ₂₀,₀₀₀ ʏᴇᴀʀꜱ. ᴏɴᴇ-
ᴇɪɢʜᴛ (₁₂.₅%) ᴏꜰ ᴛʜᴇ ᴘᴀʀᴇɴᴛ ɪꜱᴏᴛᴏᴘᴇ ʀᴇᴍᴀɪɴꜱ ɪɴ ᴀ ꜱᴀᴍᴘʟᴇ. ʜᴏᴡ ᴏʟᴅ ɪꜱ ᴛʜᴇ ꜱᴀᴍᴘʟᴇ?
₃. ɪꜰ ᴛʜᴇ ᴀᴍᴏᴜɴᴛ ᴏꜰ ᴛʜᴇ ᴘᴀʀᴇɴᴛ ɪꜱᴏᴛᴏᴘᴇ ɪɴ ᴛʜᴇ ᴏʀɪɢɪɴᴀʟ ꜱᴀᴍᴘʟᴇ ᴏꜰ ᴀ ʀᴏᴄᴋ ʜᴀᴅ ʙᴇᴇɴ ₄₈ ɢʀᴀᴍꜱ,
ᴀʙᴏᴜᴛ ʜᴏᴡ ᴍᴜᴄʜ ᴡᴏᴜʟᴅ ʜᴀᴠᴇ ʙᴇᴇɴ ʟᴇꜰᴛ ᴀꜰᴛᴇʀ ᴛʜʀᴇᴇ ʜᴀʟꜰ-ʟɪᴠᴇꜱ?
₄. ᴡʜᴀᴛ ᴘᴇʀᴄᴇɴᴛ ᴏꜰ ᴛʜᴇ ᴏʀɪɢɪɴᴀʟ ᴄᴀʀʙᴏɴ-₁₄ ʀᴇᴍᴀɪɴꜱ ɪɴ ᴀ ꜱᴀᴍᴘʟᴇ ᴀꜰᴛᴇʀ ₁₁,₄₆₀ ʏᴇᴀʀꜱ?
₅. ɪꜰ ᴀ ʀᴏᴄᴋ ᴡᴀꜱ ᴅᴇᴛᴇʀᴍɪɴᴇᴅ ᴛᴏ ʙᴇ ᴀʀᴏᴜɴᴅ ₃.₉ ʙɪʟʟɪᴏɴ ʏᴇᴀʀꜱ ᴏʟᴅ, ᴡʜᴀᴛ ᴘᴇʀᴄᴇɴᴛᴀɢᴇ ᴏꜰ ᴛʜᴇ
ᴏʀɪɢɪɴᴀʟ ᴘᴏᴛᴀꜱꜱɪᴜᴍ-₄₀ ᴡᴏᴜʟᴅ ʙᴇ ʟᴇꜰᴛ ɪɴ ᴛʜᴀᴛ ʀᴏᴄᴋ ꜱᴀᴍᴘʟᴇ?
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