M-GMAT question

[Stormgal]

Originally Posted by Vakul

my approach:

320 + 5x = 580 - .41x; x = # of days after price is same;

solving for x; x is approximately 48, thus the requiremd price is 320 + 5 * 48 = 560 cents = $5.6

took about 2 mins to solve

Nice short cut! But how did you get the -.41x - ins't it -1.41?

[Vakul]

Originally Posted by Stormgal

Nice short cut! But how did you get the -.41x - ins't it -1.41?

it is decreasing at the rate of which is .41x

[arjmen]

Hey,

Looked strangely like upper 5th - lower 6th physics to me. You're given initial prices (velocities) and rates of increase/decrease (acceleration/deceleration).

Time for prices to equate being the same,

(P-320)/(5x) = (P-580)/(-0.4x), where P is the price when the commodities
are equally expensive
=> 0.4P - 128 = 2900 - 5P

=> P = 3028/5.4, which approximates to 560 cents or $5.60


Note: equation for motion under constant acceleration is, final velocity = initial velocity + rate of acceleration * time