Write a digit in the blank space of each of the following numbers so that the number formed is divisible by 11 :
(a) 92 __ 389 (b) 8 __ 9484
Answers
Answer:
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Step-by-step explanation:
6. A train travels some distance with a speed of 30 km/h and returns with a speed of 45 km/h . Calculate the average speed of the train .
7. A train 100 m long moving on a straight level track passes a pole in 5 s . Find (a) the speed of the train (b) the time it will take in to cross a bridge 500 m long .
8. A car travels along a straight lion for first half time with speed 40 km/h and the second half time with speed 60 km/h. find the average speed of the car.
9. A body starts rolling over a horizontal surface with an initial velocity of 0.5 m/s² . Due to friction , its velocity decreases at the rate of 0.05 m/s² . How much time will it take for the body to stop ?
10. A car travelling at 36 km/h speed upto 72 km/h in 5 second. what is it acceleration ? If the same car stops in 20 second , what is the retardation ?
Answer:
answer is 6
Step-by-step explanation:
Let the required unknown digit be x Then,
Sum of digits at odd places from right = 9 + 3 + 2 = 14 Sum of digits at even places from right = 8 + x +9 = 17 + x
∵ Number is divisible by 11.
∴ Difference of digits will be 0 or 11.
⇒ (17+x)−14= 0 or 11
⇒ 17+x−14=0 or 11
⇒ x+3= 0or 11 Taking difference 0,
0,x+3=0
⇒ x=03=−3 (not possible) Taking difference 11,
x=3=11 So, required digit to write in the blank space is 11
(b) Let the required unknown digit be x. Then, number be
Sum of digits at odd places from right = 4 + 4 + x = 8 + x
Sum of digits at even places from right = 8 + 9 + 8 = 25
∵ Number is divisible by 11.
∴ Difference of digits will be 0 or 11.
⇒ 25−(8+x) = 0 or 11
⇒ 258x = 0 or 11
⇒ 17x = 0 or 11 Taking difference 0,
17−x=0
⇒x=17+0
⇒x=17
but 17 is not a single digit number, so it is not possible
Taking difference 11,
17-x =11
⇒ x = 17-11= 6
So, required digit to write in the blank space is 6