How to change the woocommerce price?

How to Change the WooCommerce Price via Functions.php

Show a discounted price on WooCommerce products without editing the price in the database.

function return_custom_price($price, $product) {
    global $post, $blog_id;
    $price = get_post_meta($post->ID, '_regular_price');
    $post_id = $post->ID;
    $price = ($price[0]*2.5);
    return $price;
}
add_filter('woocommerce_get_price', 'return_custom_price', 10, 2);

OR

function return_custom_price($price, $product) {
    global $post, $blog_id;
    $product = wc_get_product( $post_id );
    $post_id = $post->ID;
    $price = ($price*2.5);
    return $price;
}
add_filter('woocommerce_get_price', 'return_custom_price', 10, 2);