Class 8: Decimals – Exercise 6C – ICSE / ISC / CBSE Mathematics Portal for K12 Students

Question 1: Express using decimals:

(i) $408$ paise in rupees (ii) $17$ rupees $86$ paise in rupees

(iii) $673$ mm in meters (iv) $72$ cm in kilometres

(v) $481$ mg in grams (vi) $92$ kg $45$ g in kilograms

Answer:

(i) $408$ paise in rupees $= 4.08$ Rupees

(ii) $17$ rupees $86$ paise in rupees $= 17.86$ Rupees

(iii) $673$ mm in meters $= 6.73$ meters

(iv) $72$ cm in kilometres $= 0.00072$ Kilometres

(v) $481$ mg in grams $= 0.481$ grams

(vi) $92$ kg $45$ g in kilograms $= 92.045$ kilograms

$\\$

Question 2: Aditya traveled $28.96$ km by car while Sriraj traveled $91.48$ km. Who traveled more and by how much?

Answer:

Siraj traveled more because $91.48 > 28.96$

Siraj traveled $(91.48 - 28.96) = 62.52$ Km

$\\$

Question 3: A trader bought a notebook for $27.50$ , a book for Rs. $198.43$ and a pen for Rs. $145.65$ . He sold all the three things for Rs. $375$ . Find his profit or loss.

Answer:

Total cost to the trader $= 27.50 + 198.43 + 145.65 = 371.58$ Rs.

Total Selling Price $= 375$ Rs.

Profit = Selling Price – Cost Price $= 375 - 371.58 = 3.42$

$\\$

Question 4: By how much should $491.18$ be decreased to get $209.76$ ?

Answer:

$491.18 - x = 209.76$

Therefore $x = 281.42$

$\\$

Question 5: The cost of one electric oven is Rs. $75$ . Find the cost of $47$ such electric ovens.

Answer:

Cost of $47$ electric ovens $= 2489.75 \times 47 = 117018.25$ Rs.

$\\$

Question 6: One gram of gold costs Rs. $40$ . How much does a bracelet made of $48.28$ g of gold cost?

Answer:

The bracelet cost $= 3197.40 \times 48.28 = 154370.472$ Rs.

$\\$

Question 7: A car covers $9.7$ km on one liter of petrol. How much distance will it cover in $52.56$ litres of petrol?

Answer:

Distance covered $= 9.7 \times 52.56 = 509.832$

$\\$

Question 8: Find the average of the numbers $17.56, 22.43, 91.35$ and $48.3$ .

Answer:

$\displaystyle \text{ Average } = \frac{(17.56 + 22.43 + 91.35 + 48.3)}{4} = 44.91$

$\\$

Question 9: The perimeter of a polygon is $25.34$ cm. If the length of each side of the polygon is $3.62$ cm, then find the number of sides of the polygon.

Answer:

$\displaystyle \text{ Number of sides of the polygon } = \frac{25.34}{3.62} = 7$

$\\$

Question 10: How many pieces of plywood, each $0.55$ cm thick, are required to make a pile $2.53$ m high?

Answer:

$\displaystyle \text{ Number of pieces } = \frac{(2.53 \times 100)}{0.55} = 460$

$\\$

Question 11: A sum of Rs. $6512$ was divided among $100$ boys and girls in such a way that each boy gets Rs. $60$ and each girl gets Rs. $52.40$ . Find the number of girls.

Answer:

Let the number of girls be $x$

$x \times 52.40 + (100-x) \times 73.60 = 6512$

$\displaystyle x = \frac{848}{21.2} = 40$

$\\$

Question 12: An employee may claim~ $50$ for each km which he travels by taxi and~ $9.25$ for each km he drives his own car. If in a particular day he claimed Rs. $779$ for travelling a distance of $80$ km, how many km did he drive his own car?