Question 1135838
Add their rates of pumping
Newer pump:
[ 1 pool drained ] / [ 4 hrs ]
Older pump:
[ 1 pool drained ] / [ 6 hrs ]
Working together:
[ 1 pool drained ] / [ t hrs ]
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{{{ 1/4 + 1/6 = 1/t }}}
Multiply both sides by {{{ 12t }}}
{{{ 3t + 2t = 12 }}}
{{{ 5t = 12 }}}
{{{ t = 2.4 }}}
2 hrs and 24 min