Answer :
Answer:
5536 calculators
Step-by-step explanation:
We integrate the function dx/dt to obtain the number of new calculators between beginning of the 3rd week and end of week 4. Note that beginning of 3rd week is the same as end of 2nd week. So, [tex]\int\limits^4_2 {\frac{dx}{dt} } \, dx[/tex]= [tex]\int\limits^4_2 {5000 (1 - \frac{100}{(t +12)^{2} }) } \, dx[/tex]
Let u = t + 12, then [tex]\frac{du}{dt}[/tex]= 1. So, du = dt. We also change the limits of our integration. So, when t = 2, u = 2 + 12 = 14 and when t = 4, u = 4 + 12 = 16
Then [tex]\int\limits^4_2 {5000(1 -\frac{100}{(t+12)^{2} } )} \, dx[/tex] = ∫₁₄¹⁶ [tex]{5000(1 -\frac{100}{u^{2} } )} \, du = 5000[ u + \frac{100}{u} ][/tex]₁₄¹⁶ = [tex]5000[16 + \frac{100}{16} - (14 + \frac{100}{14} )] = 5000 [16 - 14 + \frac{100}{16} - \frac{100}{14} ] = 5000 [2 + \frac{100}{16} - \frac{100}{14} ] = 5535.7[/tex]
≈ 5536 calculators