Question 1020280
Let {{{ s }}} = plane's speed for A to B
{{{ 1.2s }}} = plane's speed from B to A
Let {{{ t }}} = plane's time in hrs going from A to B
{{{ 9.1667 - t }}} = plane's time in hrs going from B to A
( I converted 10 min to .1667 hrs )
-----------------------------
Trip from A to B:
(1) {{{ 2200 = s*t }}}
Trip from B to A:
(2) {{{ 2200 = 1.2s*( 9.1667 - t ) }}}
-----------------------------
(1) {{{ s = 2200/t }}}
Plug (1) into (2)
(2) {{{ 2200 = 1.2*( 2200/t )*( 9.1667 - t ) }}}
(2) {{{ 2200/1.2 = 2200*( 1/t )*( 9.1667 - t ) }}}
(2) {{{ t/1.2 = 9.1667 - t }}}
(2) {{{ t*( 1 + 1/1.2 ) = 9.1667 }}}
(2) {{{ 1.8333t = 9.1667 }}}
(2) {{{ t = 5 }}}
-------------
(1) {{{ s = 2200/t }}}
(1) {{{ s = 2200/5 }}}
(1) {{{ s = 440 }}} mi/hr
From A to B, the speed was 440 mi/hr
-------------
check:
(2) {{{ 2200 = 1.2s*( 9.1667 - t ) }}}
(2) {{{ 2200 = 1.2*440*( 9.1667 - t ) }}}
(2) {{{ 2200 = 528*9.1667 - 528t }}}
(2) {{{ 2200 = 4840 - 528t }}}
(2) {{{ 528t = 2640 }}}
(2) {{{ t = 5 }}}
OK