Discussion in 'Cambridge O Levels' started by OakMoon!, Apr 21, 2011.

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how to do the highlighted question?

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3. ### Binyamine

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4. ### A*****

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5. ### Zeerak 420

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Ok so this question is tough.

Speed of sparrow is x km/h in STILL air.

When wind is blowing at 1 KM/H, sparrow takes 5 hours to fly 12 km to nest and 12 km back again. She goes out directly into win and returns with wind behind her. Find Normal speed.

6. ### aneeqgenius7

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Last edited: Apr 28, 2017
7. ### Thought blocker

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Voulme of cylinder = pi r^2 h
Volume of outter cylinder(VO) = pi (3.5 + r)^2 (20)
volume of inner cylider (VI)= pi r^2 (20)
Volume of solid = VO - VI
3000 = VO - VI
Solve for r
r = 5.07

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8. ### aneeqgenius7

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thanks

9. ### rid_aaaa

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can anybody please explain questions related to upperbond and lowerbond

10. ### Thought blocker

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Post the question. We will see where we can help u.

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thank you so much

12. ### A*****

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No pblm

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13. ### Enferno

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part b anyone?

4024_s15_qp21_q2

14. ### A*****

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15. ### Enferno

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You cant use cos rule here. How to solve without that.

16. ### A*****

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But y can't v use it? It's not written in the question that v can not use it

17. ### A*****

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I don't think that there is any other way of solving it

18. ### Enferno

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I mean yes we can use it here. I'm looking for a way to solve without it.
Now I don't think there is.
Thank you by the way

19. ### A*****

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No there isn't... in the mark scheme as well the same one is given

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20. ### whyareallnamestaken

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21. ### Anon_Assassin

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We always use this in finding the area of a graph. (UPPERBOUND - LOWERBOUND)
For example in this graph,

We will find the area by subtracting the blue curve from the red curve.
This is also used when a line intersects the graph at more than two points.