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Total of Arun’s marks in Sanskrit and Mathematics together are 80 more than his marks in Science. His average marks in the three subjects are 100. What are his marks…

The mean of $1^{2}, 2^{2}, 3^{2}, 4^{2}, 5^{2}, 6^{2}, 7^{2}$ is. A. 10 B. 20 C. 30 D. 40 Answer: Option B Show Answer Solution(By Apex Team) $\begin{aligned}&1^2+2^2+3^2+\ldots.+n^2=\frac{n(n+1)(2n+1)}{6}\\ &\therefore1^2+2^2+3^2+\ldots.+7^2=\left(\frac{7\times8\times15}{6}\right)=140\\ &\text{…

If the mean of 5 observations x, x + 2, x + 4, x + 6 and x + 8 is 11, then the mean of the last three observations…

Company C sells a line of 25 products with an average retail price of Rs. 1200. If none of these products sells for less than Rs. 420 and exactly 10…

The average of x1, x2, x3 and x4 is 16. Half the sum of x2, x3, x4 is 23. What is the value of x1? A. 17 B. 18 C.…

The average of 2, 7, 6 and x is 5 and the average of 18, 1, 6, x and y is 10. What is the value of y? A. 5…

If the mean of a, b, c, is M and ab + bc + ca = 0, then the mean of $\mathbf{a}^{2}, \mathbf{b}^{2}, \mathbf{c}^{2}$ is. A. $\mathrm{M}^{2}$ B. $3 \mathrm{M}^{2}$…

A student was asked to find the arithmetic mean of the numbers 3, 11, 7, 9, 15, 13, 8, 19, 17, 21, 14 and x. He found mean to be…

The total marks obtained by a student in Physics, Chemistry and Mathematics together is 120 more than the marks obtained by him in Chemistry. What is the average marks obtained…

The arithmetic mean of first 11 natural numbers is A. 5 B. 5.5 C. 6.0 D. 6.5 Answer: Option C Show Answer Solution(By Apex Team) $\begin{aligned}&\text{ Required mean }\\ &=\left(\frac{1+2+\ldots\ldots+11}{11}\right)\\…