Zadanie 1a
Initially w=3, p=1/3 and charge is 1. (i) Show that the probability a of still running with charge 1 after exactly two ticks is 2/9. (ii) Find the probability b that full charge is reached for the first time on tick 4.
- Materiał graficzny
Zadania wzorowane na pytaniach z tego arkusza: te same umiejętności, format i punktacja, inne dane i kontekst. Treści arkusza IB nie publikujemy.
W bazie 14 zadań z tego arkusza, razem 55 punktów, każde z kluczem i schematem punktowania.
Initially w=3, p=1/3 and charge is 1. (i) Show that the probability a of still running with charge 1 after exactly two ticks is 2/9. (ii) Find the probability b that full charge is reached for the first time on tick 4.
Under the same w=3, p=1/3 settings, a run is still active at charge 1 after tick 4. State the probability that it is again active at charge 1 after the next two ticks.
Now let w=4 and p=1/3. Express R₂ in terms of R₁ and R₃.
For w=4 and p=1/3 it is known that R₁=1/15 and R₃=7/15. Find R₂.
For general 0<p<1 with p≠q, replace Rₙ by (p+q)Rₙ in the recurrence and prove Rn+1 − Rn = (q/p)(Rn − Rn−1).
(i) Use R₀=0 to express R₂−R₁ in terms of p,q,R₁. (ii) Show that R3 − R2 = (q/p)2R1. (iii) Deduce the general expression for Rₙ−Rₙ₋₁.
(i) By adding successive differences, or otherwise, prove . (ii) Given R1 = [1 − q/p]/[1 − (q/p)w], deduce Rn = [1 − (q/p)n]/[1 − (q/p)w].
The upward-tick probability is now 0.498. A run starts with m charge units and stops successfully when it has accumulated 12 additional units, so capacity is w=m+12. Find the smallest positive integer m giving at least an 85% chance of success.
A route has u=4, v=4, w=7. Find t.
(i) Express in terms of a,b,c,d. (ii) Hence express w in these integers.
Take z1 = 4 + 8i, z2 = c + 7i. (i) Show that w=16c−56. (ii) Show that the only possible positive integer c are 4 and 5. (iii) For c=5, find u,v,w,t.
Use 39 = 12 + 22 + 32 + 52 and the complex construction to find one valid route with t=39.
For a route define z = (v + wi)/(t − u). Show that the route (48,54,16;74) gives z = (27 + 8i)/13.
For the route (48,54,16;74), the generating numbers also satisfy . (i) Use t−u to prove c²+d²=13. (ii) Given c>d, find z₁ and z₂.
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