MATH 101 HOMEWORK 10
Due on Wednesday Dec. 1, 2004.
For full credit, show all work. Calculators are not allowed, except as indicated below.
1. (5 marks) A bank determines that the waiting time for a customer’s call to be answered
by a representative is modelled by an exponential density function whose expectation k
depends on the number of representatives they employ. If the bank wants 90% of the calls
to be answered within the first 7 minutes, what value of k should it aim for? (You may
use a calculator to finish the computations.)
2. (10 marks) Solve the differential equations:
(a) y 0 =
1+x
, y(1) = −4,
xy
(b) xy 0 − 3y = x4 cos x.
3. (5 marks) End of term: everyone gets 5 marks for free!
This homework covers Sections 7.8 and 7.9. Additional recommended exercises: Section
7.9: 1–16.
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