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A target has concentric circles with radii of 2cm, 10cm, and 20cm. What is the probability that a dart that randomly hits the target will hit within: a) the 2cm circle b) the outer ring
test 45-- i don't get #4
ReplyDeleteFirst, you must know that the (degree) measure of an arc and the length of an arc are two different, yet related, things.
ReplyDeleteCan you calculate the circumference of the circle? Yup, it's pi(d), in this case 30pi.
Do you know the ratio of the arc to the full circumference? Yes, it's 150/360 or 5/12.
Hopefully, the answer you just calculated matches the answer key!
Mr. C.
Some folks asked about #13.
ReplyDeleteOnce again, start doing the things you know how to do.
You can find the area of the circle... 25pi sq units.
The area of the shaded region is 1/20 of the circle, simplifying to (5/4)pi sq units... or you could say 5pi/4 if you like.
The area of the square is clearly 100 sq units.
The ratio of the shaded region to the square is [(5/4)pi]/100, right?
Ugly fraction, but us smarty-pants types know that dividing by 100 is the same as multiplying by 1/100.
So, we end up with 5pi/400 or pi/80 as the likelihood of a random point in the square also being in the shaded region.
Easy as, well, pi (i crack me up).
Mr. C.
A target has concentric circles with radii of 2cm, 10cm, and 20cm. What is the probability that a dart that randomly hits the target will hit within:
ReplyDeletea) the 2cm circle
b) the outer ring
hmmm... why would I ask you this question?
I didnt understand number 34 on teat 30 could someone help me?
ReplyDeletesorry test 30
ReplyDelete