On selling 17 balls at Rs.720, there is a loss equal to the cost price of 5 balls. What is the cost price of a ball?

Options

A. Rs43
B. Rs60
C. Rs55
D. Rs34

Answer

To solve the problem step by step, we will follow these instructions:

### Step 1: Understand the given information
We know that:
- Selling price (SP) of 17 balls = Rs. 720
- Loss is equal to the cost price of 5 balls.

### Step 2: Define the variables
Let the cost price (CP) of one ball be Rs. K. Therefore, the cost price of 17 balls will be:
\[ \text{CP of 17 balls} = 17K \]

### Step 3: Express the loss in terms of K
According to the problem, the loss is equal to the cost price of 5 balls:
\[ \text{Loss} = 5K \]

### Step 4: Use the formula for loss
We know that:
\[ \text{Loss} = \text{CP} - \text{SP} \]
Substituting the values we have:
\[ 5K = 17K - 720 \]

### Step 5: Rearrange the equation
Now, we can rearrange the equation to isolate K:
\[ 5K + 720 = 17K \]
\[ 720 = 17K - 5K \]
\[ 720 = 12K \]

### Step 6: Solve for K
Now, divide both sides by 12 to find K:
\[ K = \frac{720}{12} \]
\[ K = 60 \]

### Conclusion
The cost price of one ball is Rs. 60.