1 journal = 280 grams
3 journals = 280 * 3
280 * 3 = 840
Total weight of 3 journals = 840 grams
Answer:

Step-by-step explanation:
see the attached figure to better understand the problem
step 1
Find the length side KJ
In the right triangle JKM
Applying the Pythagoras Theorem

we have


substitute



simplify

step 2
Find the value of cosine of angle MJK in the right triangle JKM

substitute the values

simplify
-----> equation A
step 3
Find the value of cosine of angle MJK in the right triangle JKL

we have

----> remember equation A
substitute the values

Simplify

Answer: 0.813
Step-by-step explanation:
Let A be the event describes the number of residents believed that the amount of violent television programming had increased over the past 10 years.
& B be the event describes the number of residents believed that the amount of violent television programming had decreased over the past 10 years.
Given : n(A)=721 ; n(B)=454 ; n(A∩B)=362
We know that ,

i.e. 
Also, the total number of U.S. residents surveyed n(S)= 1,000
Then, the proportion of the 1,000 U.S. residents believed that either the amount of violent programming had increased or the overall quality of programming had decreased over the past 10 years will be :-

Hence, the required answer = 0.813