You decrease your product price by $10 in market A but leave it unchanged in market B. Sales in A rise from 840 units per week to 940 while sales in B also rise from 770 to 790. The difference-in-difference estimate of the effect of the price change is:

80 units.

Explanation:

Change in Sales of Market A =940units -840units = 100 units

Change in Sales of Market B= 790units -770 units = 20units.

Difference-in-difference estimate of the effect of the price change is = Change in sales of Market A - Change in sales of Market B = 100units -20 units = 80 units.

bd = 9 cm

step-by-step explanation:

in a 30°-60°-90° triangle, the ratio of side lengths is 1 : √3 : 2. that is, the longest side (hypotenuse) is twice the length of the shortest side.

all of the triangles in your geometry are 30°-60°-90° triangles. ac is the hypotenuse of δacd, and the short side of δabc.

the short side ad of δacd will be half the length of ac, so 3 cm. the hypotenuse ab of δabc will be twice the length of ac, so 12 cm. segment bd is the difference of the lengths ab and ad, so is

bd = ab -ad

bd = 12 cm - 3 cm = 9 cm

comment on side length ratios

you can figure the ratios of side lengths in a 30°-60°-90° triangle by considering the trig ratios of the angles. or you can figure the length of the altitude of an equilateral triangle of side length 2 using the pythagorean theorem.