1) Most weather forecasts protest themselves very well by attaching probabilitiies to their forecasts, such as "The probability of rain today is 40%." Then, if a particular forecast is incorrect, you are expected to attribute the error to the random behavior of the weather rather than to the inaccuracy of the forecast. To check the accuracy of a particular forecast, records were checked only for those days when the forecast predicted rain "with 30% probability." A check of 25 of those days indicated that it rains on 10 of the 25. Do these datat disagree with the forecast of a "30% probability of rain"? Explain.
2007-02-10 21:30:01 · 4 answers · asked by KING CHAN 1 in Science & Mathematics ➔ Mathematics
Use the binomial theroem to solve this.
n=25
p= probability of happenening =.3
q= 1-p (not happening)=.7
mean = n x p =25 x .3 = 7.5
sd = sqroot ofn x p x q 25 x .3 x .7=5.25 = sqroot =2.29
10-7.5/2.29= 1.09
1.645>1.09
fail to reject the null hypothesis
no, the data agrees with the with projected probability
2007-02-11 00:16:16 · answer #1 · answered by James O only logical answer D 4 · 0⤊ 0⤋
Not at all. There is no contradiction in the above. The 30% probability is for that particular day i.e. there is 30% chance of rain on a particular day. It does not mean that there will be rain on 30% of the days.
2007-02-10 21:48:26 · answer #2 · answered by Nimish A 3 · 0⤊ 0⤋
clouds move, so depending on the mass of cloud, will determine what percentage is given, if your constantly on the move you will know that you can travel through a quick 2 minute shower or a 5 minute downpour, with these it is unreal to say where they will fall or when they actually fizzle out
2007-02-10 21:48:09 · answer #3 · answered by Anonymous · 0⤊ 0⤋
the theoretical probability is 0.3
the observed probability is 10/25 =0.4
so you have t = 0.4-0.3/((0.3*0.7)/25)0.5 =1.08
theoretically possible
2007-02-10 22:01:33 · answer #4 · answered by maussy 7 · 0⤊ 0⤋