Small tug boats pull cruise ships up and down rivers to prevent them from grounding. Cruise ships anchor 18 km away from the river port. A tug boat can travel 12 km downstream in the same time it takes it to travel 8 km upstream. If the speed of the current is 6 km/h, calculate the travel time it takes for the tug boats to go upstream from the cruise ship to the river port and then downstream back to the cruise ship.

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At wind speeds above 1000 centimeters per second (cm/sec), significant sand-moving events begin to occur. wind speeds below 1000 cm/sec deposit sand and wind speeds above 1000 cm/sec move sand to new locations. the cyclic nature of wind and moving sand determines the shape and location of large dunes. at a test site, the prevailing direction of the wind did not change noticeably. however, the velocity did change. fifty-nine wind speed readings gave an average velocity of x = 1075 cm/sec. based on long-term experience, σ can be assumed to be 245 cm/sec. (a) find a 95% confidence interval for the population mean wind speed at this site. (round your answers to the nearest whole number.) lower limit cm/sec upper limit cm/sec