Question 167934
The distance, {{{2240}}}, is the same for both planes
For 1st plane:
(1) {{{d = r[1]*t[1]}}}
For 2nd plane:
(2) {{{d = r[2]*t[2]}}}
(3) {{{r[1]*t[1] = r[2]*t[2]}}}
It is given that {{{r[1] = 280}}} mi/hr
From (1)
(1) {{{d = r[1]*t[1]}}}
{{{2240 = 280*t[1]}}}
{{{t[1] = 8}}}
The 2nd plane leaves 45 min later and arrives 15 min earlier,
so it spends 1 hr less in the air than the 1st plane
{{{t[2] = t[1] - 1}}}
From (3)
{{{280*t[1] = r[2]*(t[1] - 1)}}}
{{{r[2] = 280t[1] / (t[1] - 1)}}}
{{{r[2] = 280*8 / (8 - 1)}}}
{{{r[2] = 2240 / 7}}}
{{{r[2] = 320}}} mi/hr
check answer:
(3) {{{r[1]*t[1] = r[2]*t[2]}}}
{{{280*8 = 320*7}}}
{{{2240 = 2240}}}
OK