Lesson Example Discussion Quiz: Class Homework |
Step-5 |
Title: Averages |
Grade: 8-a Lesson: S3-L2 |
Explanation: Let us verify the answer here with the steps. |
Description:
Step | Type | Explanation | Answer |
---|---|---|---|
1 |
Problem |
The average weight of P, Q, and R is 60 kg. The weight of Q is 20 kg less than P’s weight and R’s weight is 25 kg less than P’s weight. What will be the average of P, Q, R, and S if S weighs 2 kg more than R? |
|
2 |
Hint |
Formula used |
\$"Average" = "Sum of set of numbers" / "Amount of numbers in set"\$ |
3 |
Step |
Average weight of P, Q and R |
60kgs |
4 |
Step |
On Simplification |
\$(P + Q + R)/3 = 60\$ |
5 |
Step |
On Cancellation |
\$P + Q + R = 60 \times 3 = 180\$ → (1) |
6 |
Step |
Let "x" be the weight |
|
7 |
Step |
According to the problem, |
P = x, Q = x - 20, R = x - 25 → (2) |
8 |
Step |
Substitute |
the values in equation(1) |
9 |
Step |
On Cancellation |
\$x + x - 20 + x - 25 = 180\$ |
10 |
Step |
On Cancellation |
\$3x= 180 + 45 = 225\$ |
11 |
Step |
On Cancillation |
\$x= 225/3 = 75\$ |
12 |
Step |
Substituting x in equation(2) |
P = 75, Q = 55, R = 50 Since S is 2 more than R then S = 52 |
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