Consider a vibrating quarter-circular membrane, 0 < r < a, 0 < θ < π/2, with u = 0 on the entire boundary. [Hint: You may assume without derivation that λ > 0 and that product solutions u(r, θ, t) = φ(r, θ)h(t) = f(r)g(θ)h(t) satisfy ∇2φ + λφ = 0 dh dt = −λkh d2g dθ2 = −μg r d dr r df dr + (λr2 − μ)f = 0.]

Solve the initial value problem if u(r, θ, 0) = g(r, θ), ∂u ∂t (r, θ, 0) = 0.

Martha has a deck of cards. she has lost some of the cards, and now the deck only contains nine spades, eleven diamonds, eight clubs, and twelve hearts. martha predicts that whenever she draws a card from the deck without looking, she will draw a club one-fifth of the time. which activity would best allow martha to test her prediction? a. randomly draw a card from the box and see if it is a club. b. randomly draw a card. then, continue to draw another card until all eight clubs are drawn. c. randomly draw and replace a card 120 times. then, observe how close to 30 times a club is drawn. d. randomly draw and replace a card 100 times. then, observe how close to 20 times a club is drawn.

Need asap. solve for the following inequality

Calculate the missing value. round the answer to on decimal place. start with 70, increase it by 21%, and end up with