13. The mean score of Vasu in 3 tests is 46 marks. How many marks should he score in the fourth test so that the mean score of the 4 tests is 50 marks?

Step-by-step explanation:

Let,

Marks in fourth test = x

We know that

Mean = Sum of observation/Total observation

=> 46 = Sum/3

=> 46 × 3 = Sum

=> 138 = Sum

Now,

=> 50 = Sum of three observation + x/4

=> 50 = 138 + x/4

=> 50 × 4 = 138 + x

=> 200 = 138 + x

=> 200 - 138 = x

=> 62 = x

Hence,

he should score 62 marks in fourth test

62

Step-by-step explanation:

several ways of doing this, but I'm going to give the long and comprehensive method,

recall that mean  = total sum of marks / number of tests

in the first case, we are given

mean = 46 and number of test = 3

from this we can find the total number of marks of 3 tests by simply substituting the given values into the formula above

mean  = total sum of marks   / number of tests

46 = total sum of marks / 3

total sum of marks = 3 x 46

total sum of marks = 138  (for 3 tests)

in the second case, we are told that the number of tests is now 4 and the mean is 50 marks, using the same formula, we can find out the new total sum of marks for 4 tests

mean  = total sum of marks   / number of tests

50 = total sum of marks / 4

total sum of marks = 4 x 50

total sum of marks = 200 (for 4 tests)

number of marks for 4th test

= sum of marks for 4 tests - sum of marks for 3 tests

= 200 - 138

= 62  (answer)

hope this helps

30 miles

step-by-step explanation:

we know that 60 seconds equals 1 minute and 60 minutes 1 hour

44 ft       60 sec     60 min     158400   ft

  *   *   =

1 sec       1 min       1 hour         hour

we know that there are 5280 ft per mile

158400   ft       1 mile         30 miles

  *   =

1   hour               5280 ft     1 hour

so in 1 hour   it can travel 30 miles