You were on the right track. Here are two ways to go about it.
• By definition of conditional probability,
Pr[A | B] = Pr[A and B] / Pr[B]
Out of the total 100 participants in the survey, there are 18 people that both have a positive attitude and are over 35, so
Pr[positive and over 35] = 18/100
Out of the 100 pariticipants, 40 are over 35, so
Pr[over 35] = 40/100
Then the conditional probability you want is (18/100) / (40/100) = 18/40 = 9/20.
• There are 40 people over 35 in the survey. You want the probability that someone randomly chosen from this group has a positive attitude, of which there are 18. Hence the probability is 18/40 = 9/20.
Answer:
2380.13195
Step-by-step explanation:
2193.67÷200=10.96835
10.96835×17=186.46195
2193.67+186.46195=2380.13195
Answer: 554
Step-by-step explanation:
Formula we use to find the sample size :
Given : Standard deviation : 
Margin of error : E=one quarter hour = 0.25 hour
Two-tailed , Critical value use for 0.95 degree of confidence:
i.e. 
Hence, the required sample size = 554
i.e. 554 executives should be surveyed.
Greatest Common Factor - GCF
Factors of 24: 1; 2; 3; 4; 6; 8; 12; 24
Factors of 60: 1; 2; 3; 4; 5; 6; 10; 12; 15; 20; 30; 60
Factors of 72: 1; 2; 3; 4; 6; 8; 9; 12; 18; 23; 24; 36; 72
<span>GCF(24; 60; 72) = 12
</span>other method
24|2 60|2 72|2
12|2 30|2 36|2
6|2 15|3 18|2
3|3 5|5 9|3
1| 1| 3|3
1|
GCF(24; 60; 72) = 2 · 2 · 3 = 12
