<u>Answer:</u>
5, 7
<u>Step-by-step explanation:</u>
The mode of the numbers is 5, which means that 5 should be the most common card (highest frequency). Therefore the cards should have at least one more 5 among them.
Considering that 5 is one of the hidden cards and x is the other,
• Using the equation for the mean:


⇒ 
⇒ 
This means 5 and 7 are the hidden cards.
It's 768 sqaure centimeters
Downstream DATA:
distance = 12 miles
time = 2 hours
rate = 12/2 = 6 mph
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Upstream DATA:
distance = 12 miles
time = 4 hrs
rate = 12/4 = 3 mph
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Equations:
Downstream: b + c = 6
Upstream::: b - c = 3
------
Add to get:
2b = 9
b = 4.5 mph (speed of the boat in still water.)
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Solve for "c":
b + c = 6
4.5 + c = 6
c = 1.5 mph (speed of the current)
The answer is 1.5 mph