# Thread: standard deviation in probabilty??? help

1. ## standard deviation in probabilty??? help

Miguel buys a large bottle and a small bottle of juice. The amount of juice that the manufacturer puts in the large bottle is a random variable with a mean of 1024 ml and a standard deviation of 12 ml. The amount of juice that the manufacturer puts in the small bottle is a random variable with a mean of 506 ml and a standard deviation of 3 ml. If the total amount of juice in the two bottles can be described by a normal model, what's the probability that the total amount of juice in the two bottles is more than 1548.6 ml?

2. Originally Posted by arslan
Miguel buys a large bottle and a small bottle of juice. The amount of juice that the manufacturer puts in the large bottle is a random variable with a mean of 1024 ml and a standard deviation of 12 ml. The amount of juice that the manufacturer puts in the small bottle is a random variable with a mean of 506 ml and a standard deviation of 3 ml. If the total amount of juice in the two bottles can be described by a normal model, what's the probability that the total amount of juice in the two bottles is more than 1548.6 ml?
The mean of the normal distribution is 1024 + 506 and the variance is 12 + 3.

Now calculate Pr(X > 1548.6).

3. Originally Posted by mr fantastic
The mean of the normal distribution is 1024 + 506 and the variance is 12 + 3.

Now calculate Pr(X > 1548.6).
thank you for your help but how do i go about calculating Pr(X > 1548.6) i am confused and new to this variable stats.

4. Originally Posted by arslan
thank you for your help but how do i go about calculating Pr(X > 1548.6) i am confused and new to this variable stats.
You know X ~ normal(mean = 1024 + 506, variance = 12 + 3). And you should have been taught how to calculate probabilities that follow a normal distribution. So where are you stuck in finding Pr(X > 1548.6)?