+0  
 
0
103
1
avatar

The eyesight of 7477 women aged 30 to 39 who were employed in Royal Ordnance factories was assessed. Each eye was graded separately on a scale from 1 (very good) to 4 (poor). The results are shown in the table below.

 

 

left eye grade

 

total

 

 

1

2

3

4

 

right

1

1520

266

124

66

1976

eye

2

234

1512

432

78

2256

grade

3

117

362

1772

205

2456

 

4

36

82

179

492

789

total

 

1907

2222

2507

841

7477

One woman is selected at random from these 7477 women.

What is the probability that this woman has grade 1 or 2 eyesight in both eyes?

What is the probability that this woman does not have grade 4 eyesight in her left eye?

 Jun 11, 2020
edited by Guest  Jun 11, 2020
 #1
avatar+21953 
0

The table is nearly impossible to read; also, I can't find a way for the numbers in the first row to sum to 1976.

 

Anyway:

What is the probability that a woman, selected at random, has grade 1 or 2 eyesight in both eyes?

--  Add up four numbers:

    the number with grade 1 in left eye and grade 1 in right eye;

    the number with grade 1 in left eye and grade 2 in right eye;

    the number with grade 2 in left eye and grade 1 in right eye;

    the number with grade 2 in left eye and grade 2 in right eye;

    and divide this total by the total number of women.

 

What is the probability that this woman does not have grade 4 eyesight in her left eye?

--  Find the entry for grade 4 eyesight in her left eye; subtract this from the total number of women;

    divide this answer by the total number of women.

 Jun 11, 2020

6 Online Users