(c) 4
Let the marks obtained in 5 subjects be 6x, 7x, 8x, 9x and 10x.
Average score = 60%
\(\therefore\) \(\frac{6X+7X+8X+9X+10X}{5}\) = \(\frac{60}{100}\) \(\Rightarrow\) \(\frac{40X}{5}\) = \(\frac{60}{100}\)
\(\Rightarrow\) x = \(\frac{60\times5}{100\times40}\) = \(\frac{3}{40}\) = 0.075
\(\therefore\) The marks are 0.45, 0.525, 0.6, 0.675 and 0.75, i.e., 45%, 52.5%, 60%, 67.5% and 75%
\(\therefore\) Number of papers in which the marks exceed 50% = 4.