Question

.
20. A car starts running at speed of 40 kmph. The speed :
of car is increases by 2 km at the end of every one
hour. What will be distance covered at the end of
ten hours from start of journey?
a) 590 km b ) 480 km​

Answer 1

Step-by-step explanation:

A car starts running at a speed of 40 kmph.

After 1 hour,speed will be:(40+2)=42 kmph.

After 2 hours,speed will be :(42+2)=44 kmph.

After 3 hours,speed will be :(44+2)=46 kmph.

After 4 hours,speed will be:(46+2)=48 kmph.

After 5 hours,speed will be:(48+2)=50 kmph.

After 6 hours,speed will be:(50+2)=52 kmph.

After 7 hours,speed will be:(52+2)=54 kmph.

After 8 hours,speed will be:(54+2)=56 kmph.

After 9 hours,speed will be:(56+2)=58 kmph.

After 10 hours,speed will be:(58+2)=60 kmph.

Total distance covered by the car is:

(42+44+46+48+50+52+54+56+58+60)=510 km.

Answer 2

Given :-----

• Speed of car = 40km/h
• speed increase 2km at the end of every hour .

To Find :----

• Distance coverd by car at the end of 10 hours..

$\Large\underline{\underline{\sf{Solution}:}}$

in First hour car travel = 40km

in second hour car travel = 42 km

in third hour car travel = 44km

so, these speed form An AP series , with first term(a) as = 40km , and common difference is 2km.

we have to find sum of first 10 terms of AP .

we know that ,,,

$\large\red{\boxed{\sf Sn = \frac{n}{2}[2a + (n - 1)d]}}$

putting values we get,,,

$\blue{S_{10} = \frac{10}{2} (2 \times 40 + 9 \times 2)} \\ \\ \implies \pink{S_{10} = 5(80 + 18)} \\ \\ \implies \green{S_{10} = 490 \: km}$

$\red{ \textbf{Hence , the Car will travel 490km.}} \: \\ \\ \orange{\textbf{Total Distance in 10 Hours.}}$