Mathematical Operations with Significant Figures

Significant Figures Quiz – Real-Life Applications

Test your understanding of significant figures in multiplication, division, addition, and subtraction using practical real-life situations.

1. Fuel Consumption

A car travels 245.6 km using 12.4 L of petrol. What is the fuel efficiency?

A) 19.8 km/L B) 19.81 km/L C) 19.806 km/L D) 20 km/L

2. Area of a Solar Panel

A rectangular solar panel has dimensions 1.25 m and 0.840 m. What is its area?

A) 1.05 m² B) 1.050 m² C) 1.1 m² D) 1.0500 m²

3. Water Remaining in a Tank

A tank initially contains 125.8 L of water. After using 37.42 L, how much water remains?

A) 88.38 L B) 88.4 L C) 88.40 L D) 88 L

4. Total Length of Wood Pieces

Three wooden pieces have lengths 2.35 m, 4.2 m, and 1.478 m. What is the total length?

A) 8.028 m B) 8.03 m C) 8.0 m D) 8.0280 m

5. Mass of Rice Packed

A machine fills packets with 2.45 kg of rice each. If 18 packets are filled, what is the total mass?

A) 44.1 kg B) 44.10 kg C) 44.100 kg D) 44 kg

6. Speed of a Cyclist

A cyclist covers 32.5 km in 1.84 h. What is the average speed?

A) 17.7 km/h B) 17.66 km/h C) 17.663 km/h D) 18 km/h

7. Remaining Wire Length

A spool contains 75.62 m of wire. A technician uses 12.3 m. What length remains?

A) 63.32 m B) 63.3 m C) 63.320 m D) 63 m

8. Total Grocery Bill

A customer buys items costing ₹125.45, ₹87.2, and ₹19.876. What is the total bill?

A) ₹232.526 B) ₹232.53 C) ₹232.5 D) ₹233

9. Volume of a Box

A box has dimensions 15.2 cm, 8.4 cm, and 3.25 cm. What is its volume?

A) 410 cm³ B) 414.96 cm³ C) 415.0 cm³ D) 414.9 cm³

10. Cost per Kilogram of Apples

A shopper pays ₹246.5 for 4.25 kg of apples. What is the cost per kilogram?

A) ₹58.0/kg B) ₹58.00/kg C) ₹58.000/kg D) ₹57.9/kg

Answer Key

1. A
2. A
3. B
4. C
5. A
6. A
7. B
8. C
9. A
10. A

Detailed Solutions

1. Fuel Consumption

\[ \frac{245.6}{12.4}=19.80645 \]

Division uses the least number of significant figures. 12.4 has 3 significant figures.

\[19.80645 \approx 19.8\]

2. Area of Solar Panel

\[1.25 \times 0.840 = 1.05\]

Both measurements have 3 significant figures.

Answer: 1.05 m²

3. Water Remaining

\[125.8-37.42=88.38\]

Subtraction follows the least number of decimal places.

\[88.38\approx88.4\]

4. Total Length

\[2.35+4.2+1.478=8.028\]

Least decimal places = 1.

\[8.028\approx8.0\]

5. Mass of Rice

\[2.45\times18=44.1\]

18 packets is an exact counted quantity, so it does not limit significant figures.

6. Speed of Cyclist

\[\frac{32.5}{1.84}=17.663\]

Rounded to 3 significant figures:

\[17.7\text{ km/h}\]

7. Remaining Wire

\[75.62-12.3=63.32\]

Rounded to 1 decimal place:

\[63.3\text{ m}\]

8. Grocery Bill

\[125.45+87.2+19.876=232.526\]

Rounded to 1 decimal place:

\[232.5\]

9. Volume of Box

\[15.2\times8.4\times3.25=414.96\]

Least significant figures = 2.

\[410\text{ cm}^3\]

10. Cost per Kilogram

\[\frac{246.5}{4.25}=58.0\]

Rounded to 3 significant figures.