Find out the correct number to replace the question mark.
Source: Beijing Aidi International School summer test (2018-08-21). Author: 坦途国际教育
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You are correct. The answer is 9.
The first line has 3 bears with hats totaling 21. So a bear with a hat is 21/3 = 7.
The next line is 2 sets of a bear in a bus plus a bear in a hat totaling 19. So we know a bear in a bus is (19-7)/2 = 6.
Next is a hat, a bear in a bus, and a bear in a hat totaling 15. So we know a hat is 15-6-7=2.
Now that we know a hat is 2, a bear must be 5 (7-2). If a bear is 5, than a bus is 1 (6-5)
A hat is 2, a bear is 5, and a bus is 1. That makes the last line 5 + 4*1 which does equal 9.
Adding neater formatting but here is solution:
The key to this puzzle is attention to detail about what each image truly is
For the first line:
We have 3 bears and 3 hats. This adds up to 21 meaning a bear + a hat = 7.
Next we have to look at the third line:
In this line we have a bear with a hat (7), a hat and a bus with a bear. In total then we have a bus of unknown value and 2 bears with hats valued at 7 each. To get the total sum of 15 an empty bus must equal 1 (15-(2x7)).
Back to the second line now:
There are 2 buses with a hat-less bear and one bear with a hat (7). Since each bus is worth 1 and the bear with hat is worth 7, subtracting 9 from 19 leaves 10 for the value of two bears and 5 for the value of each individual bear.
Value of a hat:
Since a hat and a bear is 7 and a bear is 5, a hat is worth 2.
To recap: A bear without hat is 5, two hats will be 4 and a bus is 1. 1x4 (BEDMAS/PEDMAS) is still 4. All that is left is 4 + 5 which equals 9.
Let t be the number of teddy bears, h hats and b buses. Then the equations are:
and we want to know:
Gaussian elimination tells us the answer is:
$t=5, h=2, b=1$, therefore $t+2hb=9$.
but there is a quick way:
From (1) $t+h=7$. From (3) $b=1$. From (2) and (3), $t-h=3 \implies t=5, h=2$.
Observation is the key in this puzzle.
3pig_with_cap=21 , =>1pig_with_cap=7
2bus_with_pig + 1pig_with_cap =19 , => 2bus_with_pig=12, =>1bus_with_pig=6
1cap + 1bus_with_pig + 1pig_with_cap= 15, =>1cap=2,
1pig= 1pig_with_cap - 1cap= 7-2=5
1bus = 1bus_with_pig - 1pig = 6-5=1,
=> 1pig + ((2*cap)*bus) = 5+ 2*2*1=9
9 is the answer
The answer of that puzzle is 8
the solution of that puzzle is like ....
In the first line the sum of 3 teddy with cap is 7+7+7=21
In the next line the two buses seems to have a point 6 as an
individual so 6+6+7=18
In the third line a cap having 2 points so 2+6+7=15 So
further on teddy has no cap so 7-2= 5 ....further on the teddy is not
in the bus so 6-5=1 so by calculating all that 5+2+1=8 So the answer
of that puzzle is 8
The bear, hat and bus can each be described as a certain variable. Let's use B = Bear, H = Hat, and S = Bus.
Using this, we can rewrite the equations as:
[B + H + B + H + B + H = 21] [B + S + B + S + B + H = 19] [H + B + S + B + H = 15]
Each of these simplify down to:
[B + H = 7] [3B + 2S + H = 19] [2B + 2H + S = 15]
And the question becomes
B + 2H * S = ?
Now we have a system of three equations and three variables.
Solving the system returns B = 5, H = 2, and S = 1
B + 2H * S = 5 + 2(2) * 1 = 9