The Least amount of money we need is 130
She already has 45
She needs "e" more
Therefore:
45 + e ≥ 130
Answer: 2.460
Step-by-step explanation:
The formula of Margin of Error for (n<30):-

Given : Sample size : n= 18
Level of confidence = 0.90
Significance level : 
Using the t-distribution table ,
Critical value : 
Standard deviation: 
Then, we have

Hence, the margin of error (ME) of the confidence interval with a 90% confidence level = 2.460
The answer is :
0.18181818
But you can also write it like this