Unitary Method — Case Study Based Questions

Sajal went to the grocery store to purchase some vegetables. He bought 2.5 kg potatoes for ₹70; 4.5 kg onions for ₹135, 1.5 kg ladyfinger for ₹48 and 3 kg tomatoes at the rate of ₹29 per kg.

1. If he gave a ₹500 note to the shopkeeper, then the amount of money he got back, is :
   (a) ₹150
   (b) ₹160
   (c) ₹140
   (d) ₹180

2. The cost of 4 kg potatoes will be :
   (a) ₹118
   (b) ₹120
   (c) ₹112
   (d) ₹116

3. The cost of 2.5 kg ladyfinger will be :
   (a) ₹80
   (b) ₹85
   (c) ₹90
   (d) ₹75

4. The total bill for a purchase of 3 kg potatoes, 2 kg onions and 4 kg tomatoes will be :
   (a) ₹275
   (b) ₹260
   (c) ₹248
   (d) ₹265

Answer

1. Cost of 3 kg tomatoes = ₹ (29 x 3) = ₹ 87

Total cost of vegetables = ₹ (70 + 135 + 48 + 87) = ₹ 340

Amount of money he got back = ₹ (500 − 340) = ₹ 160

Hence, option (b) is the correct option.

2. Cost of 2.5 kg potatoes = ₹ 70

Cost of 1 kg potatoes = ₹ $\Big(\dfrac{70}{2.5}\Big)$ = ₹ 28 [Less potatoes, Less cost]

Cost of 4 kg potatoes = ₹ (28 x 4) = ₹ 112 [More potatoes, More cost]

Hence, option (c) is the correct option.

3. Cost of 1.5 kg ladyfinger = ₹ 48

Cost of 1 kg ladyfinger = ₹ $\Big(\dfrac{48}{1.5}\Big)$ = ₹ 32 [Less ladyfinger, Less cost]

Cost of 2.5 kg ladyfinger = ₹ (32 x 2.5) = ₹ 80 [More ladyfinger, More cost]

Hence, option (a) is the correct option.

4. Cost of 1 kg potatoes = ₹ $\Big(\dfrac{70}{2.5}\Big)$ = ₹ 28

Cost of 3 kg potatoes = ₹ (28 x 3) = ₹ 84

Cost of 1 kg onions = ₹ $\Big(\dfrac{135}{4.5}\Big)$ = ₹ 30

Cost of 2 kg onions = ₹ (30 x 2) = ₹ 60

Cost of 1 kg tomatoes = ₹ 29

Cost of 4 kg tomatoes = ₹ (29 x 4) = ₹ 116

Total bill = ₹ (84 + 60 + 116) = ₹ 260

Hence, option (b) is the correct option.