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The speed of a stream is 2 km/ hr. A boat goes 32 km. and comes back to the starting point in 12 hours. What is the speed (in km/hr.) of the boat in still water? |
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Answer» Step-by-step explanation: ᴜᴘsᴛʀᴇᴀᴍ sᴘᴇᴇᴅ= (6 - 2) = 4 ᴋᴍᴘʜ ᴅᴏᴡɴsᴛʀᴇᴀᴍ sᴘᴇᴇᴅ = (6 + 2) = 8 ᴋᴍᴘʜ ᴜᴘsᴛʀᴇᴀᴍ ᴛɪᴍᴇ = 32/4 = 8 ʜᴏᴜʀs ᴅᴏᴡɴsᴛʀᴇᴀᴍ ᴛɪᴍᴇ = 32/8 = 4 ʜᴏᴜʀs ᴛᴏᴛᴀʟ ᴛɪᴍᴇ = 8 + 4 = 12 ʜᴏᴜʀs ᴀʟᴛᴇʀɴᴀᴛᴇ ᴍᴇᴛʜᴏᴅ : ᴜᴘsᴛʀᴇᴀᴍ sᴘᴇᴇᴅ= (6 - 2) = 4 ᴋᴍᴘʜ ᴅᴏᴡɴsᴛʀᴇᴀᴍ sᴘᴇᴇᴅ = (6 + 2) = 8 ᴋᴍᴘʜ ᴀᴠᴇʀᴀɢᴇ sᴘᴇᴇᴅ ғᴏʀ ᴡʜᴏʟᴇ ᴊᴏᴜʀɴᴇʏ = 2 X 4 x 8 / ( 4 + 8 ) = 5 ⅓ ᴋᴍᴘʜ => ᴛᴏᴛᴀʟ ᴛɪᴍᴇ = 64/5 ⅓ = 12 ʜᴏᴜʀs |
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