Question Detail

The average of four consecutive odd numbers is 24. Find the largest number.

Answer: Option B

Explanation:

Let the numbers are x, x+2, x+4, x+6, then
\begin{aligned}
=> \frac{x+(x+2)+(x+4)+(x+6)}{4} = 24
\end{aligned}

\begin{aligned}
=> \frac{4x+12)}{4} = 24
\end{aligned}

\begin{aligned}
=> x+3 = 24 => x = 21
\end{aligned}

So largest number is 21 + 6 = 27

1. Marks of a student were wrongly entered in computer as 83, actual marks of that student were 63. Due to this mistake average marks of whole class got increased by half (1/2). Find the total number of students in that class.

Answer: Option D

Explanation:

Suppose total number of students are = X
\begin{aligned}
Total increase = x*\frac{1}{2} = \frac{x}{2} \\
=> \frac{x}{2} = 83-63 = 20 \\
=> x = 40
\end{aligned}

2. A motorist travel to a place 150 km away at an avearge speed of 50 km/hr and returns ar 30 km/hr.His average speed for the whole jouney in km/hr is

36.5 km/hr
37.5 km/hr
35.5 km/hr
34.5 km/hr

Answer: Option B

Explanation:

Average speed will be

\begin{aligned}

\frac{2xy}{x+y} km/hr

= \frac{2(50)(30)}{50+30} km/hr
\end{aligned}

= 37.5 km/hr

3. Find the sum of first 30 natural numbers

Answer: Option C

Explanation:

Sum of n natural numbers
\begin{aligned}
= \frac{n(n+1)}{2}
\end{aligned}

\begin{aligned}
= \frac{30(30+1)}{2} = \frac{30(31)}{2} = 465
\end{aligned}

4. The average of four consecutive odd numbers is 24. Find the largest number.

Answer: Option B

Explanation:

5. Average of 10 numbers is zero. At most how many numbers may be greater than zero

Answer: Option D

Tanvee 11 years ago

If its odd number then we need to to take x,x+1,x+3,x+5.... why we are taking even number?

mastguru 11 years ago replied

Hello Tanvee,
We are taking X as an odd number,
so, other consecutive odd number will be x+2 and another will x+4 and so on..
Lets say 1 is odd number, then next will 1+2 =3, 1+4 =5.. and so on.
In this way we are solving this problem.
Admin 11 years ago

Thanks Nagendar. It was a typing mistake. Question was about four consecutive odd numbers.
We appreciate your feedback.
nagendar 11 years ago

here x is an even number. but you got x=21(which is not even number). so consecutive even numbers are: 2x,2x+2,2x+4,2x+6.