. Let's find which one is the best buy.
a) 6 pencils for Rs 48 or 5 pencils for Rs 50.
b) 4 kg of potatoes for Rs 120 or 6 kg of potatoes for Rs 150.
c) 9 sweets for Rs 135 or 10 sweets for Rs 160.
d) 7 kg of grapes for Rs 700 or 8 kg of grapes for Rs 720.



Answer :

Let's analyze each pair of options step-by-step to determine the best buy in each case.

### a) 6 pencils for Rs 48 or 5 pencils for Rs 50

First, calculate the cost per pencil for each option:

1. 6 pencils for Rs 48:
- Cost per pencil [tex]\( = \frac{48}{6} = 8 \)[/tex]

2. 5 pencils for Rs 50:
- Cost per pencil [tex]\( = \frac{50}{5} = 10 \)[/tex]

Comparing the two:
- 6 pencils for Rs 48 (Cost per pencil: Rs 8)
- 5 pencils for Rs 50 (Cost per pencil: Rs 10)

Best buy: 6 pencils for Rs 48 (Cost per pencil: Rs 8)

### b) 4 kg of potatoes for Rs 120 or 6 kg of potatoes for Rs 150

Next, calculate the cost per kg for each option:

1. 4 kg of potatoes for Rs 120:
- Cost per kg [tex]\( = \frac{120}{4} = 30 \)[/tex]

2. 6 kg of potatoes for Rs 150:
- Cost per kg [tex]\( = \frac{150}{6} = 25 \)[/tex]

Comparing the two:
- 4 kg of potatoes for Rs 120 (Cost per kg: Rs 30)
- 6 kg of potatoes for Rs 150 (Cost per kg: Rs 25)

Best buy: 6 kg of potatoes for Rs 150 (Cost per kg: Rs 25)

### c) 9 sweets for Rs 135 or 10 sweets for Rs 160

Now, calculate the cost per sweet for each option:

1. 9 sweets for Rs 135:
- Cost per sweet [tex]\( = \frac{135}{9} = 15 \)[/tex]

2. 10 sweets for Rs 160:
- Cost per sweet [tex]\( = \frac{160}{10} = 16 \)[/tex]

Comparing the two:
- 9 sweets for Rs 135 (Cost per sweet: Rs 15)
- 10 sweets for Rs 160 (Cost per sweet: Rs 16)

Best buy: 9 sweets for Rs 135 (Cost per sweet: Rs 15)

### d) 7 kg of grapes for Rs 700 or 8 kg of grapes for Rs 720

Lastly, calculate the cost per kg for each option:

1. 7 kg of grapes for Rs 700:
- Cost per kg [tex]\( = \frac{700}{7} = 100 \)[/tex]

2. 8 kg of grapes for Rs 720:
- Cost per kg [tex]\( = \frac{720}{8} = 90 \)[/tex]

Comparing the two:
- 7 kg of grapes for Rs 700 (Cost per kg: Rs 100)
- 8 kg of grapes for Rs 720 (Cost per kg: Rs 90)

Best buy: 8 kg of grapes for Rs 720 (Cost per kg: Rs 90)

### Summary of Best Buys:
- Pencils: 6 for Rs 48 (Cost per pencil: Rs 8)
- Potatoes: 6 kg for Rs 150 (Cost per kg: Rs 25)
- Sweets: 9 for Rs 135 (Cost per sweet: Rs 15)
- Grapes: 8 kg for Rs 720 (Cost per kg: Rs 90)