00:01
In this problem, we are given that on an average, a family spends about $400 every month on groceries.
00:10
And the standard deviation, well, that's given as $50, and we are required to find the percentage of the families.
00:18
That spends between $450 and $5 .50 every month on groceries.
00:25
So basically if we consider x here as the amount spent on groceries every month, and we will consider this to be following normal distribution, then basically we will find the probability that x is greater than 450, but less than 550.
00:43
So here we will first use this formula and get the z score corresponding to these two data values.
00:50
So when we plug in the value of x as 450, along with the mean and standard division, the z score we will get is 450 minus 400 over 50, which simplifies to 1.
01:03
And similarly, corresponding to the data value 550, the z score would be 4 .550 minus 400 over 50, which is equal to 3...