# Thread: [solved] 45 45 90

1. ## [solved] 45 45 90

Hello!
A balloonist lands on a square region 12 m on a side. What's the probability of landing on the X?

2. Originally Posted by dire
Hello!
A balloonist lands on a square region 12 m on a side. What's the probability of landing on the X?
The probability (making a number of assumptions) is the ratio of the area of
the cross to that of the square.

The area of the cross is the area of the square minus 4 times the area of one
of the triangles.

hence the required prob is:

(144-4*8)/144=7/9

opps.. area of one triangle is 16 not 8 so prob is:

(144-4*16)/144=5/9

RonL

3. Total area is $12 \times 12 = 144$.

Area of 4 right triangles = $16 \times 4$.

Then the probability is: $\frac{144- 64}{144} = \frac{5}{9}$