Question

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?​

Answer 1

Step-by-step explanation:

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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