Answer with explanation:
Let p be the proportion of adults have heard of the new electronic reader.
Given claim : The accompanying technology display results from a test of the claim that 38% of adults have heard of the new electronic reader.
i.e.
Then , the set of hypothesis will be :-

Since, the alternative hypothesis is two tailed , so the test is two-tailed test.
Also, it is given that the sample size : 
Number of adults showed that they have heard of a new electronic reader=522
So the sample proportion for adults have heard of the new electronic reader : 
The test statistic for proportion is given by :-
By using standard normal distribution table , the P-value for two tailed test corresponds to the obtained z-value =
For first pound it is = $2.41
For next six, = 0.41 * 6 = $2.46
Remaining = 7.99 - (2.41 + 2.46) = 7.99 - 4.87 = 3.12
Now, additional pounds = 3.12 / 0.39 = 8
Total weight = 1 + 6 + 8 = 15
In short, Your Answer would be 15 pounds
Hope this helps!