Urgent math help please Stats

Could you please show your work

1) For a normal distribution with a mean of 30 and a standard deviation of 5, the probability of getting a value less than 20 or greater tahn 35 is

2)On a recent test, scores of 54 and 64 corresponded to z-scores of -1.0 and 1.5 respectively. Find the class mean and average.

3)the marks of 1200 students who wrote a Math diploma exam are normally distributed. The diagram below indicates 169 students had a mark above a particular z-score. The z-score is

4)Determine the mean and standard deviation for each set of sport data
a. 72,74,73,76,74,71,75,76,72,77
b.(100m dash (sec)) 10.8,10.6,10.8,9.9,10.2,10.3,10.4,10

Use the formula z=(X-饾泹)/饾潏

1) z=(X-饾泹)/饾潏=(35-30)/5=5/5=1

P(X>35)=P(z>1)=1-P(z<1)=1-0.8413=0.158鈥?br>

2) z=(X-饾泹)/饾潏
-1=(54-饾泹)/饾潏
-饾潏=54-饾泹 or 饾泹-饾潏 =54 ..(1)

1.5=(64-饾泹)/饾潏


1.5饾潏=64-饾泹 or 饾泹+1.5饾潏=64 ...(2)

Solve the system by multiplying (1) by -1 and adding them

饾泹-饾潏 =54 ..(1)
饾泹+1.5饾潏=64 ...(2)
-----------------
2.5饾潏=10
饾潏=10/2.5= 4

Substitute 饾潏 in (1)
饾泹-4 =54 then 饾泹=58

I think you meant the mean and standard deviation not the mean and average.


3)There is no diagram

But I can guess

1200-169=1031

Find proportion of those who got less than z is

1031/1200=0.8592 this is the area under z so call it a

P(z


4) Use a calculator or the formulas for mean and SD

a) mean=74 SD=2

b) mean=10.4 SD=0.24