The cost price of a swim-suit, C.P.=$8
Option 1:
If the selling price is marked up by 25%, the new selling price is
![S.P.=C.P.+C.P.* 25\%](https://img.qammunity.org/2021/formulas/mathematics/high-school/yvfo1o7rfcp5vvtlvh9h1a0h74jt8hbhsd.png)
![=8+8*(25)/(100)](https://img.qammunity.org/2021/formulas/mathematics/high-school/7gw2vyuh35ucm9xkdkxbl2d426wscnag10.png)
=8+2
=10
So, the selling price will be $10 which is the same as the mentioned selling price.
Hence, this option is correct.
Option 2:
If the selling price is marked up by 40%, the new selling price is
![S.P.=C.P.+C.P.* 40\%](https://img.qammunity.org/2021/formulas/mathematics/high-school/gua2nvph5s5jqm9m78fqao9gyj1rxh7huo.png)
![=8+8*(40)/(100)](https://img.qammunity.org/2021/formulas/mathematics/high-school/qpn68ah0zl8yot9uigr83d0t9ui8lo702l.png)
=8+3.20
=11.20
So, the selling price will be $11.20 which is not the same as the mentioned selling price, $7.50.
Hence, this option is wrong.
Option 3:
If the selling price is marked up by 55%, the new selling price is
![S.P.=C.P.+C.P.* 55\%](https://img.qammunity.org/2021/formulas/mathematics/high-school/btecceq1g89kg843hrmc6aog4lukobaay7.png)
![=8+8*(55)/(100)](https://img.qammunity.org/2021/formulas/mathematics/high-school/76jftqxa2iaapdvd8fi81kw477in2bndov.png)
=8+4.40
=12.40
So, the selling price will be $12.40 which is not the same as the mentioned selling price, $5.50.
Hence, this option is wrong.
Option 4:
If the selling price is marked up by 70%, the new selling price is
![S.P.=C.P.+C.P.* 70\%](https://img.qammunity.org/2021/formulas/mathematics/high-school/f5j9aivg80c63s6fqepmkcelw8876c1gyu.png)
![=8+8*(70)/(100)](https://img.qammunity.org/2021/formulas/mathematics/high-school/4ghh6enbd53ozvpa8iwe303z4b4xkhijnr.png)
=8+5.60
=13.60
So, the selling price will be $13.60 which is the same as the mentioned selling price.
Hence, this option is correct.
Option 5:
If the selling price is marked up by 75%, the new selling price is
![S.P.=C.P.+C.P.* 75\%](https://img.qammunity.org/2021/formulas/mathematics/high-school/q5zk5plxkiezuuskzm0p91f4tqt02q4yip.png)
![=8+8*(75)/(100)](https://img.qammunity.org/2021/formulas/mathematics/high-school/2e4t473j8m5mmm7ntqnfawf7fuyidbkvqi.png)
=8+6
=14
So, the selling price will be $14 which is the same as the mentioned selling price.
Hence, this option is correct.