Friday

January 30, 2015

January 30, 2015

Posted by **Sandra** on Friday, July 17, 2009 at 1:40am.

Upstream, downstream. Junior’s boat will go 15 miles per

hour in still water. If he can go 12 miles downstream in the

same amount of time as it takes to go 9 miles upstream,

then what is the speed of the current?

- algebra -
**Reiny**, Friday, July 17, 2009 at 7:43amlet the speed of the current be x mph

so the time taken to go 9 miles upstream (against the current) = 9/(15-x)

and the time taken to go 12 miles downstream (with the current) = 12/(15+x)

but we are told the times are the same, so

12/(15+x) = 9/(15-x)

cross-multiply

solve for x to get the speed (I got around 2.14)

**Answer this Question**

**Related Questions**

algebra - 36 Upstream, downstream. Junior’s boat will go 15 miles per hour in ...

Math - Steve's boat will go 14 miles per hour in still water. If he can go 13 ...

Intermediate Algebra - in still water, a paddle boat averages 10 miles per hour...

Math Word Problem - Steve's boat will go 14 miles per hour in still water. If he...

algebra - Rita’s boat has a top speed of 12 miles per hour in still water. While...

algebra - A boat travel 4 miles upstream with a current of 5 miles per hour. It ...

Math - Brian's boat has a top speed of 9 miles per hour in still water. While ...

Algebra - A boat can travel upstream 14 miles in same it can travel downstream 8...

intermediate algebra - a motorboat moves 25 miles per hour in still water. it ...

algebra - how do I solve this and show the work: a motorboat went upstream at 15...